On the final day of a White House summit, Obama outlined a three point plan for countering violent extremism around the world.
President Obama speaks at the U.N. General Assembly, touching on topics from terrorism to climate change. Steve Handelsman reports.
Islamist militants controlling parts of Iraq and Syria have purportedly released a new audio recording warning Americans that "you will not feel secure even in your bedrooms."
9/11 commission issues new recommendations for preventing future terrorist attacks. Jay Gray reports.
Authorities now say a sniper was behind an April attack of 17 electrical transformers in Southern California. They're now treating the incident as a terror attack.
Canadian authorities have broken up what is being described as a "major terrorist attack" that may have included targets there and in New York.
The Energy Department has been hit by a major cyber-attack.
FBI agents arrest men accused of plotting to train terrorists overseas for future attacks in America.
11 years after losing her father in the 9/11 attacks, Caitlin Leavey works to help others heal. Erika Tarantal reports.
The CIA foiled a plot by al-Qaida's affiliate in Yemen to bomb a U.S.-bound airliner around the one-year anniversary of the killing of its former leader Osama bin Laden, senior U.S. officials told NBC News.