Top five threats to national security in the coming decade.

• Author: Erwin, Sandra I.
• Position: Special Report

* Defense technologists are most successful when they hone in on specific problems. The Pentagon's research agencies and their contractors were asked in 2003 to come up with ways to foil roadside bombs in Iraq and Afghanistan, and although they did not defeat the threat entirely they did produce a number of useful detectors, jammers and other counterexplosive systems. More recently, military researchers received marching orders to help tackle the so-called "anti-access area-denial" threats, which is Pentagon-speak for enemy weapons that could be used to shoot down U.S. fighters and attack Navy ships.

The next wave of national security threats, however, might be more than the technology community can handle. They are complex, multidimensional problems against which no degree of U.S. technical superiority in stealth, fifth-generation air warfare or night-vision is likely to suffice.

The latest intelligence forecasts by the Obama administration and other sources point to five big challenges to U.S. and global security in the coming decades.

Biological Weapons: The White House published in 2009 a National Strategy for Countering Biological Threats with an underlying theme that biological weapons eventually will be used in a terrorist attack. To prevent deadly viruses from being turned into mass-casualty weapons, officials say, one of the most difficult challenges is obtaining timely and accurate insight on potential attacks. The Defense Threat Reduction Agency has a team of researchers working these problems. But they worry that the pace of research is too slow to keep up with would-be terrorists.

Nukes: Large stockpiles of nuclear weapons are tempting targets for nation-states or groups set on attacking the United States and its allies, officials assert. Black-market trade in sensitive nuclear materials is a particular concern for U.S. security agencies. "The prospect that al-Qaida or another terrorist organization might acquire a nuclear device represents an immediate and extreme threat to global security," says an administration report. No high-tech sensors exist to help break up black markets, detect and intercept nuclear materials in transit and there are no financial tools to disrupt this dangerous trade. A much-hyped Department of Homeland Security effort to detect radioactive materials at U.S. ports has been plagued by technical hiccups. Analysts believe that although a full-up nuclear weapon would be nearly impossible for an al-Qaida...