The Bush administration said it is "ramping up" America's terror defenses ahead of some upcoming events that could be al-Qaida targets.
However, White House Press Secretary Scott McClellan acknowledges there's been no spike in terrorist "chatter" monitored by U.S. intelligence. Rather, he said there's been a "continuous stream" indicating al-Qaida has operatives in America who may be plotting to strike.
He points to Saturday's dedication of the World War II memorial in Washington, the upcoming G-Eight summit in Georgia, the Fourth of July and the summer political conventions as "possible targets."
McClellan said Americans should be vigilant, because the nation "is in a serious threat period."