Expert says bioattack unlikely

Experts have said that a biological or nuclear attack on the United States by terrorist remains the nation's greatest threat but is unlikely to occur.

Scott Stewart, vice president of tactical intelligence at Stratfor, a global intelligence company, told Xinhua that terrorists are intent on attacking but lack the means to create a weapon.

According to Stewart, building a deployable weapon of mass destruction for a non-state entity such as Al-Qaeda or even for most countries is difficult. Those with access to universities, teams of scientists, proper facilities and large budget still struggle to create a usable weapon.

Additionally, the purchase of a weapon of mass destruction has become harder as the Untied States pours an estimated $1 billion per year into tracking and buying fissile material to keep it off the market.

Despite the relative difficulty in securing proper WMDs, U.S. Secretary of State Hillary Clinton told CNN in a recent interview that they remain the biggest threat to the United States.

"The biggest nightmare that many of us have is that one of these terrorist member organizations within this syndicate of terror will get their hands on a weapon of mass destruction," she said, noting that Al-Qaeda was "unfortunately a very committed,clever, diabolical group of terrorists who are always looking for weaknesses and openings."

Vice President Joe Biden has also said recently that another attack on the scale of the September 11, 2001 attacks is unlikely, though keeping WMDs out of the hands of anti-U.S. radicals remained the most pressing issue of national security for the U.S.