) -- Secretary of Homeland Security Janet Napolitano warned Americans to be vigilant of suspicious activity ahead of the 10th anniversary of the Sept. 11 terrorist attacks.

Napolitano's stated that there was not specific threat from al-Qaeda or its affiliates as the Department of Homeland Security began its "National Preparedness Month" that encourages people to learn how to prepare for disasters that range from hurricanes to acts of terror.

Secretary of Homeland Security Janet Napolitano

"As we approach the tenth anniversary of the September 11, 2001 terrorist attacks, the safety and security of the American public remains our highest priority," Napolitano said. "While there is no specific or credible intelligence ... we remain at a heightened state of vigilance and security measures are in place to detect and prevent plots against the United States should they emerge."

The spotlight was on Napolitano last week as Hurricane Irene threatened to smack the U.S. East Coast. The secretary along with FEMA Administrator Craig Fugate led their departments to help citizens before the storm and provide relief in its aftermath.

Irene caused an estimated $10.1 billion in damage, but that number was significantly lower than what was originally feared on forecasters' initial predictions.

-- Written by Joe Deaux in New York.

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