There has not been a terror attack on U.S. soil since 9/11, although there have been a number of attacks across the globe -- from Madrid and London to Casablanca and Bali -- killing hundreds and wounding thousands.
The United States Military has killed or captured more than three-fourths of the terrorist organization that plotted and carried out the September 11 attacks, and at least 10 plots have been foiled since then.
However, al Qaeda leader Osama bin Laden and his top deputy, Ayman al Zawahiri, are still on the loose and regularly appear on videotapes, audio tapes and Web postings, commenting on everything from Iraq to Mideast politics.
Al Qaeda may have lost its Afghan sanctuary, but its ideals have spawned franchises around the world.
"They are regrouping on the Internet, experimenting with technologies. They are re-energizing in homegrown types of terrorist movements in Great Britain and getting some training in Pakistan," former 9/11 Commission member Tim Roemer said.
Most Americans expect another attack on American interests.
Americans' confidence in how safe they were was shattered by the news that suspected terrorists were plotting to use liquid explosives to blow up airliners bound for the United States from Great Britain.
The alleged plot raises questions over how much security has improved in the years since 9/11
It doesn't seem like it's been five years since this day of terror. The attacks on our citizens and landmarks were a tragedy that I truly will never forget. We need to do everything in our power to ensure that nothing like this ever happens again.
Check out these 9-11 links: