President Bush spoke by phone Thursday with more world leaders to receive condolences and seek support for the United States as it struggles to recover from the most devastating terrorist attack in its history.

"We have just seen the first war of the 21st century," Bush told reporters after speaking by phone with New York Mayor Rudolph Giuliani. "I am confident there will be universal approval of the actions this government takes."

Bush placed calls to Crown Prince Abdullah of Saudi Arabia, NATO Secretary-General Lord Robertson and Silvio Berlusconi of Italy. White House spokesman Ari Fleischer said the calls were part of Bush's effort to assemble an international coalition against terrorism, and all four leaders told Bush that "they stand united with the people of the United States."

Fleischer would not say whether Bush specifically asked these leaders to provide military or economic support. "It is more than rhetorical, but I'm not prepared to go beyond that," Fleischer said.

"It is an expression of world support and world condemnation," Fleischer told reporters.

The president has asked Congress to provide billions of dollars for rescue operations, and pondered what military actions he could take to punish the terrorists. Fleischer said again Thursday that Bush maintains the authority to defend the nation and was talking with Congress about his options.

Drafts were circulated of a separate measure authorizing the administration to undertake military action under the War Powers Act. Officials said there had been some discussion of a formal declaration of war, as well, although that seemed less likely.