Electromagnetic pulse weapons capable of frying the electronics in civil airliners can be built using information and components freely available on the internet, according to counterterrorism experts. All it would take to bring a plane down would be a single but highly energetic microwave radio pulse blasted from a device inside a plane, or on the ground and trained at an aircraft coming in to land.

John Arquilla revisits his classic thesis on network warfare in light of the recent spate of terrorist "swarm" attacks and argues that the U.S. should brace itself for a similar series of attacks on the homeland.

Air Force researchers are worried about a terror group using small drones to spy on -- or even attack -- U.S. forces. So the military boffins are testing out high-powered microwave blasts, to knock the small robo-planes out of the sky.

Bruce Schneier argues that calls to ban mapping tools like Google Earth because they could be used for terrorism would harm society as much as "if we banned cars because bank robbers used them too."

Two senior Bush administration officials this week offered differing assessments of al-Qaeda's capability to carry out a major new attack against the United States.

John Mueller, a political science professor at Ohio State University, argues that there is an "almost vanishingly small" likelihood that terrorists would ever be able to acquire and detonate a nuclear weapon. In even the most likely scenario of nuclear terrorism, there are 20 barriers between extremists and a successful nuclear strike on a major city, according to Mueller.

The terrorism threat to the United States over the next five years will be driven by instability in the Middle East and Africa, persistent challenges to border security and increasing Internet savvy, says a new intelligence assessment from the U.S. Homeland Security Department. Chemical, biological, radiological and nuclear attacks are considered the most dangerous threats that could be carried out against the U.S. but are also the most unlikely because it is so difficult for al-Qaida and similar groups to acquire the materials needed to carry out such plots.

An Indian Court has been called to ban Google Earth amid suggestions the online satellite imaging was used to help plan the terror attacks that killed more than 170 people in Mumbai last month.

The terrorists who struck Mumbai last month stunned authorities not only with their use of sophisticated weaponry but also with their comfort with modern technology, including satellite imagery and VOIP Internet phones to avoid surveillance.