DHS: Attempted Attacks on U.S. at All-Time High

With attempted terror attacks in the U.S. at an all-time high, the U.S. should operate under the premise that other operatives are currently in the country and could plot an attack "with little or no warning," according to a Department of Homeland Security report obtained by CBS News.

The four-page report, "Evolving Threats to the Homeland," prepared by the Office of Infrastructure Protection, says that "the number and pace of attempted attacks in the U.S. over the past nine months have surpassed the number of attempts during any other previous one-year period."

The report highlights the growing threat of improvised explosive devices (IEDs), many of which are now delivered in vehicles - such as the recent Times Square bomb plot.