As both U.S. leaders and America's allies continue praising the top secret operation that killed 9/11 mastermind Osama bin Laden, new concerns arose in the intelligence community Tuesday of possible revenge attacks by al-Qaeda affiliated groups.
"It's a kind of situation where we need to preserve our sense of vigilance," former Vice President Dick Cheney warned. "There's every reason to believe there'll be further attacks attempted against the United States."
"And for us to spend so much time patting ourselves on the back because we got bin Laden that we miss the next attack would be a terrible tragedy," he said.
The intelligence community has differing views about just when such an attack might come. Some believe bin Laden's death may speed up plans already in the works, while others believe it could take years.
"I think we can expect it, but I think we have to be patient," former CIA Assistant Director Charlie Allen said. "I don't think we'll see an attack immediately. It can be month. It can be years. But there will be efforts to avenge the death of Osama bin Laden."
But even as leaders have urged caution, bin Laden's death has brought a sense of relief for many across the country -- even at a Muslim center in Oshkosh, Wis. The center's men say bin Laden was not one of them.
"This is a good, good day for all of the Muslim nations, especially America as well," one center member said. "So I think it's a very, very happy moment for us because we keep getting closer and closer to eliminating al Qaeda, getting rid of terrorism."
Muslim groups in Washington, D.C., also expressed relief that bin Laden is gone.
But in Gaza, the prime minister of the Hamas-led government said the killing was unjustified.
"Despite the difference in opinions and agenda between us and them, we condemn the assassination of a Muslim and Arab warrior and we pray to God that his soul rests in peace," Hamas Prime Minister Ismail Haniyeh told reporters in Gaza.
In New York City on Tuesday, the man at the center of the storm on 9/11, former Mayor Rudy Giuliani, was quick to praise President Obama.
"I think the president made exactly the right decision," he said.
Also, at the bipartisan congressional dinner at the White House Monday night, the president received a standing ovation.
On Thursday, Obama will travel to New York City and visit the former site of the World Trade Center Towers to mark the death of the world's most wanted man.