Osama bin Laden, the mastermind behind the Sept. 11, 2001, terror attacks, is dead, but Al-Qaeda operatives are still out there, sparking new fears of retaliation.
The threat has prompted a new travel warning from the U.S. Department of State for passengers traveling in and out of the United States.
Officials say that attacks from Al-Qaeda and its affiliates from around the world could be possible in the coming days.
In a worldwide travel alert, the department said there was an "enhanced potential for anti-American violence given recent counterterrorism activity in Pakistan."
The thought of a retaliatory attack was on the minds of everyone we talked with Monday at Reagan National Airport. As one traveler said, we can't let fear paralyze us.
"I was flying today and of course you're going to be a little nervous," said Sasha Evans.
Sherry Martin said she wouldn't let that keep her from traveling. "There's always reason to be concerned but you can't let it interfere with your plans for the most part," she said.
Karen Rossini said she trusts that authorities have an eye out for travelers' safety. "The government has done a good job in recent years of foiling a lot of attempts. Things we don't know anything about...and that's ok," she said.
U.S. citizens are strongly urged to limit their travel outside of their homes and hotels and avoid mass gatherings and demonstrations. The travel alert is set to expire August 1, 2011.
The department also put U.S. embassies and police authorities on alert hours after the announcement of bin Laden's death.