Writing in Slate in response to Bill McKibben's book Enough, which is about the dangers of biotechnology, robotics, and nanotechnology, Jim Holt trots out a particularly lame argument about why we have little to worry about.
Accordingly, the Princeton physicist J. Richard Gott III has calculated that we can be 95 percent confident that the human species in its present form will be around for at least another 5,100 years but not more than 7.8 million years. (This, by the way, would give us a total longevity very similar to other mammal species, which on average go extinct 2 million years after they appear.)
To be meaningful a model has to be built on realistic assumptions. A model about species extinction has to consider environmental changes. The extinction of a species is far more likely to happen if the environment that the species evolved to live in suddenly goes thru radically changes. Well, news flash of the obvious: Humans are causing rapid changes in their own environment and will continue to do so.
Humans are major agents of changes in their own environment. Many of those human-caused changes have been beneficial for human survival. Human life expectancy for the world as a whole has risen dramatically over the last couple of centuries while the human population has reached levels never before seen in the history of the species. There are even technologies under development that promise to literally halt and reverse aging and this writer is a big supporter of the accelerated development of rejuvenation technologies. But the whole point of McKibben's argument is that humans are developing technologies that could be used to create threats to the continued existence of the human species.
An argument about historical longevity of mammalian species ought at the very least take into consideration that humans are causing the death of large numbers of other species (mammalian and otherwise). Many species now face much greater threats to their continued existence than they have in the past for the simple reason that humans have developed powerful abilities to change the environment and to cause the death of other species. Humans also have developed and continue to develop various abilities to cause the death of fellow members of their species. Of course humans have also demonstrated the willingness to use those abilities. Well, the features of human nature that are the source of that willingness are not going away (unless we do genetic engineering to change human nature - which probably will happen). At the same time, the ability of humans to cause the death of fellow humans looks set to increase quite dramatically as a wide array of technologies advance.
Let us take nanotechnology as an example. Nanotech assemblers are held out to eventually provide us with the ability to build anything cheaply and easily. Well, the ability to build anything includes the ability to build nuclear weapons. It may also include the ability to create new species that can out-compete existing species. There are recent historical precedents for how that could play out. Humans in the last couple of hundred years have moved species from various parts of the globe to other locales where they have never existed before. Introduced predator species in Australia, Hawaii, and other locales are killing existing species that have no evolved defenses for dealing with those predators. Some species are being completely wiped out by human-introduced species. It is not unreasonable to think there is a chance that some humans could manage to create a life form that has the potential to so change the environment of the globe as to cause the extinction of the human race as well.
The basic question that any debate about the future dangers of technology has to answer is whether the net effect of likely technological advances in the 21st century will favor the offensive or the defensive. Optimists assume that the kinds of dangers generated by technological advances be offset by even greater abilities to create systems to protect us from these dangers. But that assumption can not be proven and there are very plausible arguments against it.
Barring a natural disaster or total collapse of industrial civiliation humans are going to become so much more powerful in this century and will become so much more capable of changing their own environment that any argument about the risk of humanity's extinction that is built from historical data of average species longevity is hopelessly naive. Arguments from historical data have embedded in them the assumption of a low probability that in any time period there will be a huge change in the environment of a species. But that assumption does not hold for humans in the next 100 years. We will gain many new capabilities to affect our environment. We do not know whether we will use those abilities wisely enough to avoid our own extinction. It would be unwise hubris to assume that we will.
A neutrino emitting weapon could neutralize nuclear bombs anywhere on the planet.
But the "muon storage ring" generator needed to propose the neutrino beam would need to be 1000 kilometres wide. It would also require 50 gigaWatts of power to operate - the same as used by the entire UK - and would cost an estimated $100 billion to construct.
However, the researchers stress that the method is well beyond the capabilities of current particle accelerators and would require substantial R&D and financial investment by many nations
Such a weapon as a defense against nukes runs up against some major problems. It has to be aimed at within a few meters of a nuke to disable it. So it is useless against a well hidden nuke. The biggest nuclear threat the United States faces in the future is probably from nukes smuggled in by terrorists. Therefore the value of this as a defense against the primary threat is questionable. Also, it would cause serious and probably fatal damage to any human hit by the beam.
Some comments in the full text of the paper draw attention to other problems with this approach: the nuke will still explode at a lower level and it will take a few minutes to make that happen.
We have shown that it is possible to eliminate the nuclear bombs from the surface of the earth utilizing the extremely high energy neutrino beam. When the neutrino beam hits a bomb, it will cause the fizzle explosion with 3% of the full strength. It seems that it is not possible to decrease the magnitude of the explosion smaller than this number at this stage. It is important to decrease this number to destroy bombs safely. We are not sure what this means when the plutonium or uranium is used to ignite the hydrogen bomb. We may just break the bomb or may lead to a full explosion. The whole process takes a matter of a few minutes in the case considered in this paper although, of course, it depends on the intensity of the neutrino beam. When the bombs are stored in the form of plutonium ball separated from the explosives, what we can do is to melt them down or vapor them away. It takes substantially longer time for this process to occur.
If it takes a few minutes to knock out a nuke then the beam device can not knock out a large number of nukes rapidly. If it can do one nuke in 3 minutes then at most it can knock out 20 nukes in an hour. Therefore it could not stop a large scale attack of ICBMs even if the beam could somehow be directed accurately to fast moving targets. Also, the nukes will still emit a small fraction of the amount of energy they would emit if they exploded normally. A particle beam designed to simply make an ICBM malfunction and explode during boost stage seems a more reasonable approach than to attempt to knock out a nuke on a travelling ICBM.
Because of the large surface area needed for the device the Moon becomes a candidate worth considering for the site of construction. Though the costs of hauling materials to the Moon to construct it would be very high it could be reduced if most of the needed materials could be mined and processed on the Moon.
Cosmic subatomic particles called muons strike the Earth continuously. Scientists at Los Alamos National Laboratory in New Mexico have demonstrated that the scattering of muons thru different types of materials can be used to detect smuggled nuclear weapons.
The high-energy particles, called muons, scatter in a highly predictable pattern when they strike dense materials like uranium or the lead used in heavy shielding, and that scattering could be picked up by a special detector, the scientists said.
Unlike X-rays muons can penetrate dense objects and produce 3 dimensional images.
In contrast, muons are highly penetrating - a typical cosmic-ray muon can pass through more than 10 metres of water - and could be used to produce radiographic images of medium-to-large objects in a short exposure time.
The muon detectors are little more than "extruded aluminium, stainless steel wires and argon gas" and the device needs no radiation source. Furthermore, unlike the X-ray and gamma-ray scanners, there is no health risk associated with the radiation dose.
Konstantin Borodzin of LANL says this method will be useful for examining large objects.
"This method shows promise as an inexpensive, harmless probe for medium to large objects, such as commercial trucks, passenger cars or sea containers, using only the natural flux of muons," Borozdin said.
As the technologies needed to develop nuclear weapons spread more widely there is an increasing need to detect attempts by terrorists to smuggle radiological and nuclear weapons.
Virologists call the world's most lethal disease organisms Level 4 pathogens. Experiments with them are confined to Biosafety Level 4, or BSL-4, labs. Those labs need to be sealed, pressurized areas designed to prevent pathogens from escaping, even in a nuclear blast.
Lab capacity is needed for testing to respond when an actual terrorist attack is suspected or known to be occurring.
While the funding includes money for two new BSL-4 labs, in Maryland and Montana, neither will be open for at least three years. Meanwhile, the four existing BSL-4 labs in the United States do not offer nearly enough space. If a biological attack occurred, creating the need for sample testing, the labs' capacity would be stretched past the breaking point, researchers say.
The other reason this type of lab space is needed is to test new vaccines and drug treatments against pathogens that would likely be used in a bioweapons attack. The lack of lab space discourages researchers from working on research for bioweapons defense against bioterrorism.
To deal with a bioterrorism attack the United States really needs highly secure labs scattered throughout the country located near major biomedical research centers. Also, the labs need an associated larger living area that scientists could move into and isolate themselves from the larger society if a major epidemic was raging. Boston, San Diego, and other cities with large concentrations of biomedical researchers should have the facilities that will allow them to put a large number of top researchers on developing counters to a plague introduced by terrorists.
But the risk of a potentially life-threatening reaction to the smallpox vaccine is between 14 and 52 per million inoculations, according to the Department of Health and Human Services, and the odds of death are one to two per million. By comparison, the chance of dying behind the wheel of a car is about 24 per million drivers per year. In other words, the fatality risk you would assume by taking the smallpox vaccine is about a 10th the risk you assume by driving around, and the reason for being vaccinated seems somewhat more compelling than, say, the need for a Slurpee.
A more complex breakdown of smallpox vaccination risks puts the risk of death from smallpox vaccination at 5 per million for babies under the age of 1 but a tenth that amount after the age of 1. Though there is not enough data to determine the risks for those after age 20.
There is a risk after vaccination of passing vaccinia on to someone who has a compromised immune system. A car driver has a 100 times greater risk of killing a pedestrian or other nonrider than to kill someone with "contact vaccinia" after getting vaccinated.
Working from data that Neff and three of his colleagues recently published in the Journal of the American Medical Association, I figure the odds of dying from "contact vaccinia," as it's called, at two to four per 10 million inoculations. In 2001, by way of comparison, every 10 million licensed drivers caused the deaths of about 300 pedestrians and other nonriders -- people who had not voluntarily assumed the risk of getting into an automobile.
There has been a lot of debate about whether getting vaccinated for smallpox is worth it. The problem with the debate is that we can't know what the Iraqi and North Korean regimes and other potential possessors of smallpox are capable of. We do not know with certainty the identity of every government that has smallpox or how well guarded their smallpox stock is. Therefore we are stuck comparing a precisely calculable and known risk of vaccination with an alternative which has risk probabilities that are not known.
Having already been inoculated for smallpox once and having emerged unscathed I'd be inclined to get inoculated again if the opportunity to do so was made available to the general public. I have a rather pessimistic view of what terrorists and nasty regimes are capable of.
It is possible to develop a safer form of smallpox vaccine using DNA vaccines. DNA vaccines can cause the body to make protein antibodies while at the same time the inability of the DNA vaccines to replicate eliminates the risk from infection. The problem with such an alternative vaccine is that it would take years to develop and so would be of no help in reducing the threat of vaccination or bioterrorist attack in the short term.
DNA vaccines have an additional benefit: They can be much more rapidly modified to deal with bioengineered weaponized versions of pathogens that are immunologically different fom naturally occurring versions of pathogens. The US Navy's Naval Medical Research Center has been working on DNA vaccines.
Building on the innovative DNA vaccine models developed by Carucci and his fellow Navy researchers, the three captains and their colleagues have quietly worked in laboratories at NMRC to develop the next generation of vaccines against deadly diseases, whether they are naturally occurring or bio-engineered weapons.
Traditional vaccines have saved countless millions, but have their limitations. They take years to develop and can be difficult and costly to manufacture. They need constant refrigeration, and generally cannot be mixed to inoculate against more than one disease at a time. And there's always the danger of side effects.
But now, Carucci, Mateczun, Galloway and their colleagues may have taken the first steps to a potential new generation of vaccines, which is expected to be safer, cheaper, stable, have fewer side effects, be more effective against a wider variety of diseases and easier to administer.
They are expected to have what the researchers call "agility" -- that is, they can be retailored quickly to become "just-in-time" inoculations against bacteria, viruses or other pathogens that have emerged or re-engineered to make existing vaccines ineffective.
"One of the potential advantages of this agile vaccine technology, which the Navy is a leader in developing, is that production from start to finish might take a matter of months, not years," said Rear Adm. Steven Hart, MC, head of the Navy's medical research programs.
Even months is still too long a time. What the US and other Western nations need is the ability to sequence a new version of a pathogen and manufacture a new version of a DNA vaccine in a matter of days.
In a sign of the times the American Society for Microbiology has instituted a system for review of research articles that contain potentially dangerous information.
As a publisher of 11 peer-reviewed journals in the microbiological sciences, the ASM is on the front lines in dealing with publication of information that could be misused, Atlas pointed out. For this reason, the ASM Publication Board has adopted policies and procedures for dealing with any manuscript that may describe misuse of microbiology or of information derived from microbiology. Reviewers alert editors, who then alerts the Editor in Chief. The Editor in Chief contacts the Chair of the ASM Publications Board, and the entire board may be involved in the disposition of the manuscript.
ASM publication policy also requires that research articles must contain sufficient detail to permit the work to be repeated by others, and authors must agree to supply materials in accordance with laws and regulations governing the shipment, transfer, possession, and use of biological materials and that such supply be for legitimate research needs.
During the period 2001-2002, 14,000 manuscripts were submitted to the ASM journals. Of these, 224 dealt with select agents. Of these, 90 were rejected—57 with non-US authors. There were 134 accepted—58 with non-US authors. Among these, 2 (<0.015%) elicited elevated concern. Each was considered by the entire Publications Board and they are to be published with modification, Atlas reported.
While this sort of measure will provide some benefit the real problem is that as technology advances it becomes easier to manipulate matter into whatever form is desired. Most of the technological advances that will make it easier to develop biological weapons will not be advances made specifically in order to make nasty pathogens. Advances that enhance general abilities to study and manipulate biological materials will make it easier to make bioweapons.
Update: The rules for when ASM journals will withhold information are less strong than the statement makes them appear. The rule seems to refer to misuse of microbiology by the actual researcher.
Ask ALL reviewers to advise the Editor, by use of the Confidential Comments section of the review form and the appropriate check-off box when it becomes available, if, in their opinion, the manuscript under review describes misuses of microbiology or of information derived from microbiology.
If a researcher has legitimate reasons to study dangerous pathogens and isn't trying to make a bioterror weapon then it doesn't sound like this rule would be invoked to possibly restrict a paper from being published even if the paper contained information directly applicable to the manufacture of bioweapons. A researcher could, for instance, describe which variations of some viral gene make that virus more or less virulent. There are certainly legitimate reasons for wanting to acquire that type of information. But that information could be easily misused by someone else who otherwise would not be able to easily figure it out.
The vast bulk of all researchers are not trying to misuse microbiological research techniques. But they are discovering information that is useful for those who do wish to use biological science to harm others.
The threat of terrorism makes dealing with nuclear waste storage problems an urgent priority.
space-saving method for storing spent nuclear fuel has dramatically heightened the risk of a catastrophic radiation release in the event of a terrorist attack, according to a study initiated at Princeton.
Terrorists targeting the high-density storage systems used at nuclear power plants throughout the nation could cause contamination problems "significantly worse than those from Chernobyl," the study found.
The study authors, a multi-institutional team of researchers led by Frank von Hippel of Princeton, called on the U.S. Congress to mandate the construction of new facilities to house spent fuel in less risky configurations and estimated a cost of $3.5 billion to $7 billion for the project.
The paper is scheduled to be published in the spring in the journal Science and Global Security.
Strapped for long-term storage options, the nation's 103 nuclear power plants routinely pack four to five times the number of spent fuel rods into water-cooled tanks than the tanks were designed to hold, the authors reported. This high-density configuration is safe when cooled by water, but would likely cause a fire -- with catastrophic results -- if the cooling water leaked. The tanks could be ruptured by a hijacked jet or sabotage, the study contends.
The consequences of such a fire would be the release of a radiation plume that would contaminate eight to 70 times more land than the area affected by the 1986 accident in Chernobyl. The cost of such a disaster would run into the hundreds of billions of dollars, the researchers reported.
Society is going to have to be gradually restructured to adjust for the danger posed by small groups waging asymmetric warfare. Technologies that are inherently less usable by terrorists should be preferred over technologies that are more easily turned against the society that uses them.
Fortune has a nice survey of a wide range of chemical and nuclear weapons detectors under development.
The neutron-scanning leader is Ancore Corp., a small company in Santa Clara, Calif., that was recently acquired by OSI, a California inspection-systems firm. Ancore's president, physicist Tsahi Gozani, who co-invented the technology in the late 1980s, has fought an uphill battle ever since to convince potential buyers that it can be cost-effective. His work is cut out for him: Among other precious parts, Ancore's $10 million scanner includes a custom-built, 30-foot-long atom smasher to generate neutron beams.
What is especially curious about this is how technologies previously useful only by particle physicists for basic research are being adapted for use to detect different types of materials.
A recent conference organised by the US National Academies of Sciences was held to debate the question of whether restrictions should be made on the publication of research that terrorists could use.
Several speakers at the conference urged that leaders in science sit down and talk with national security officials to outline what information it would make sense to keep confidential.
"Rational and well-conceived restrictions do remain necessary," Mitch Wallerstein said, a former assistant secretary of defense now at the MacArthur Foundation in Chicago.
Mr Wallerstein said universities should be more careful about who they admit and grant access to research, while the Government should look more carefully at who is granted visas.
The opposing argument is that scientists need to be able to show each other their research and to discuss their research in order to advance.
"Science is inherently a social activity," John Marburger, director of the White House Office of Science and Technology Policy, told the conference.
The problem, of course, is that there are people with malevolent intentions reading and listening to what scientists are telling each other.
Various agencies of the United States government have been putting security restrictions on research that they fund. Many researchers are resisting the new restrictions.
Before 9/11 and the anthrax attacks, most biologists would never have considered withholding results from publication. Outside of private companies and defence-related projects, the free exchange of information is a cornerstone of scientific culture. So the steps taken by the Bush administration have come as a shock to many researchers.
"For scientific openness, this has been an earthquake, an avalanche and a tidal wave rolled into one," says Steven Aftergood, who monitors government secrecy at the Federation of American Scientists in Washington DC.
Some universities are turning down grants that come with restrictions on prior review before publication of research and on the nationality of researchers. However, not all universities are balking at the new funding rules.
But the National Security Agency refused to budge from a requirement that any foreigners working on a planned project at MIT's Artificial Intelligence Laboratory be screened by the government in advance, forcing the school to turn down the money in September, Powell said.
About half of graduate students in the physical sciences and engineering come from abroad.
Lets entertain some hypotheticals. Suppose every pathogen known to humanity has its DNA sequence published on the web. Suppose nanotechnology advances far enough that affordable (lets say under $1 million and hence affordable by any decent sized international terrorist organization or rogue state) devices are developed for sale on the open market that can generate any DNA sequence and perhaps by using an existing bacteria place that sequence into an organism that then becomes the desired pathogen. The ability to make any pathogen will be available. A large body of scientific research may be available at some point in the future on how to modify pathogens to make them more virulent, to make them have a longer period of contagiousness for the host.
Suppose information is discovered to allow a pathogen to be bioengineered to have mild symptoms that mimic the symptoms of a mild cold for a couple of weeks before the host finally becomes seriously ill. Suppose other information is discovered that makes it easy to know how to modify pathogens in other ways that increase their usefulness to biological terrorists. At that point how do we stop some suicidal cult from killing a large fraction of the human population as part of their own plan to cross over to, say, rejoin with the alien spirits calling to them from a passing comet?
Suppose some research project investigating how well various devices can detect smuggled bombs discovers a way of packing a bomb that makes it impossible for existing detection devices to detect. If that method of packing is not known to terrorists and is unlikely to be discovered by them then should the scientists publish that part of their results?
Or suppose at some point in the future scientific research gets published that shows how to use then available nanotech to construct a small fusion bomb that doesn't require a fission trigger. Are we supposed to just say that the need for scientists to talk to each other trumps all other considerations?
The concern about where the graduate students in American universities come from is a valid one. Saddam's best weapons makers were educated in America. Should anyone of any ideological or religious persuasion from any country on Earth be allowed to come to the United States or other Western countries for advanced scientific and technical education?
Nanotechnology will make it possible to develop new kinds of weapons of mass destruction.
Nanotechnology has the potential to create entirely new weapons. Fourth-generation nuclear weapons are new types of nuclear explosives that would use inertial confinement fusion (ICF) facilities.
The defining technical characteristic of fourth-generation nuclear weapons is the triggering - by some advanced technology such as a superlaser - of a relatively small thermonuclear explosion in which a deuterium-tritium mixture is burnt in a device whose weight and size are not much larger than a few kilograms. Since the yield of these warheads could go from a fraction of a ton to many tens of tons of high-explosive equivalent, their delivery by precision-guided munitions or other means will dramatically increase the fire-power of those who possess them - without crossing the threshold of using kiloton-to-megaton nuclear weapons, and therefore without breaking the taboo against the first-use of WMD. Moreover, since these new weapons will use no (or very little) fissionable materials, they are expected to produce virtually no radioactive fallout.
The problem this poses is that as nanotech manufacturing equipment becomes available for purchase many more groups and countries will be able to make weapons that are currently beyond their technical ability to build. The ability to build nuclear weapons with little or no fissionable materials will remove another obstacle. Countries that are now struggling to buy and build uranium and plutonium enrichment facilities (e.g. Iraq, Iran, North Korea, and perhaps Libya) will suddenly find that the size of that problem will shrink by orders of magnitude.
The threats posed by the spread of WMD into the hands of more governments and to terrorist organizations will grow enormously as technology advances throughout the 21st century.
Aracor has developed a system that uses X-rays to look for hidden nuclear materials.
The system they developed produces high-energy X-rays that can penetrate cargo containers and common shielding materials. If the X-rays hit uranium or plutonium they induce fission reactions, splitting their nuclei into smaller fragments. In the process, neutrons are emitted that can pass through shielding materials and be picked up by a neutron detector outside.
If this system becomes deployed at every point of entry into the United States and every single piece of cargo or vehicle is examined with it it still won't prevent nuclear bombs from being smuggled into the United States.
SUNNYVALE, CA – October 2002 – Advanced Research and Applications Corporation (ARACOR), a leading manufacturer of x-ray imaging systems, announces that it has signed a Cooperative Research and Development Agreement ("CRADA") to develop and deploy technology that can detect special nuclear materials and nuclear weapons concealed within sea cargo containers or trucks. Under this CRADA, ARACOR will work with the Idaho National Engineering and Environmental Laboratory and the Los Alamos National Laboratory to optimize and deploy a new nuclear materials detection system.
"Presently, Customs inspectors are equipped with small radiation sensors ("radiation pagers") to detect the presence of special nuclear materials and radioactive isotopes. These sensors provide the first layer of defense against the nuclear materials threat," explained ARACOR’s President, Dr. R. A. Armistead. "However, to further enhance Custom’s capabilities for the interdiction of nuclear materials illicitly entering the U.S., we are using an active detection approach involving photoneutron and photofission reactions that can only be produced in fissile materials. If this new active nuclear detection technology is deployed on our Eagle® inspection system, it will be possible to automatically detect nuclear materials while routine x-ray inspections of the cargo are being conducted," Armistead added.
The Eagle is a self-contained mobile x-ray inspection system designed for inspecting cargo containers, vehicles and rail cars. This high-performance system provides a cargo penetration capability equivalent to 300 mm of steel and can form an image of a cargo container or truck in less than a minute.
Here's the problem in a nutshell: Detection systems have to succeed before the weapon reaches a high population density area. A ship has to come into a harbor and to be off-loaded in order for its cargo to be examined. Well, Ahmed the A-bomb Attacker is just going to install a remote control device or a GPS detected that will cause the nuclear bomb in some ship's cargo to go off once the ship reaches the harbor of some major US port city. That would allow them to blow up San Diego, San Francisco, Seattle, New York City, Boston, New Orleans and many other US cities. So I do not see how this detection system helps all that much.
A more clever attacker could develop a large long-range torpedo that could carry a nuclear bomb and then release it from a ship many miles off-shore with a guidance system that would deliver the bomb into a harbor before detonating. A similar approach would be to use a small surface boat that had an automatic guidance system that would keep it moving toward a port. The boat could even be made up to have a dummy at the helm so that the boat would appear to have a pilot. The boat could even use a camera feeding a video signal to a remote that had electronic means of controlling the boat.
It is extremely difficult to prevent a nuclear attack by a small group once that group gets a workable nuclear weapon. If a group has enough money and brains they can figure out any number of ways to delivering the weapon with a high probability of success.
Looking at likely technological trends for the next 30 or 40 years its hard to see how advances defensive systems can keep pace with the development of new ways to manufacture and deliver weapons of mass destruction (WMD). Advances in nanotechnology, biotechnology and other fields will make it feasible for people with less resources and skills to develop WMD. As a result,as technology advances smaller and smaller groups will be able to develop WMD. A steadily increasing number of people will be able to develop WMD. What must we to do to prevent terrorist attacks that kill tens or hundreds of millions?
The only detection system that would have a chance of stopping terrorist WMD weapons before they reach their targets would have to be absolutely monumental in scope. Ships would need to dock in automated ports in extremely low population density areas. Then their cargo could be unloaded and examined to check for WMD. All originating ports would need weapons detection systems and extensive video and other sensor systems to prevent WMD from being placed on ships headed outbound. All ships would need extensive monitoring systems on-board to prevent the addition of WMD while in transit. Major coastal population areas would require embedded passive sensor systems offshore and automated underwater, surface, airborne mobile platforms that did constant patrols looking for approaching ships and underwater craft.
Detection of WMD on approaching aircraft, ships, boats, and underwater craft is not an adequate method of defense. Another approach (and keep in mind I'm not advocating any approach; just trying to illustrate the scope of the effort required to defend against easily buildable WMD) would be to prevent WMD development by extensively monitoring the actions of every person on the planet. Once artificial intelligence is achieved this might be possible to do. Stationary and mobile monitoring of the scope required would generate so much sensor data that it could only be done if artificially intelligent computers were doing the work.
There's an even more radical approach possible for defense against WMD development by increasing numbers of governments and non-governmental organisations: genetically engineer the personalities of some or all of the human race to make them less dangerous. People could be made to be less hostile and angry or perhaps to be more empathetic and more kind and benevolent. That may well turn out to be the only approach that will work well enough to prevent catastrophic terrorism.
Technology is a way to do things. The tools of technology can be applied for good or ill. Each person must decide what to use technologies for. As technologies become more advanced the number of things that each person will be able to do will steadily increase. The problem is that technologies can more easily destroy than they can protect. Therefore, as technologies become more advanced the risk that even a very small number of hostile peope pose eventually becomes enormous. This is the biggest political problem that the human race faces in the 21st century.