Already, this week's stunning terrorist blows against America appear to have profoundly altered the Bush administration's approach to the rest of the world.
Days ago, foreign leaders were fretting that a disengaged United States was heading down a unilateralist path. Now the US is reaching out to friend and foe alike as it seeks to build an international coalition to fight the scourge of terrorism.
Suddenly, President Bush is dealing with international relations much more in the style of his father, who rallied a broad coalition to fight the Gulf War. That is important, observers say, because the task now facing the son is a similar one: working from an initial base of close allies to construct an "inclusive" coalition that doesn't end up in a clash of civilizations that would only make things worse.
Both President Bush and Secretary of State Colin Powell have spent many hours since Tuesday consulting with world leaders. They have won solid words of support for cooperation in the fight against terrorism from European leaders, as well as from Russian President Vladimir Putin and Chinese President Jiang Zemin.
The diplomatic press has paid off, at least so far. The US has won unprecedented solidarity from NATO, which on Wednesday invoked for the first time an article of its charter that in effect interprets an attack like Tuesday's in the US as an act against all 19 NATO members. The move does not obligate the members to join the US in an eventual military action, but does ensure assistance from NATO countries once the US decides to act.
China's eagerness to open channels of cooperation with the US reflects a desire to keep the US acting within the UN framework and not limiting its international response to work with the Europeans, analysts say.
Critical now, observers say, is for the Bush administration to work from this initial base to build an "inclusive" coalition of countries, including moderate Arab states and Islamic regimes. Now as during the Gulf war, anti-American sentiment runs deep in many of these countries. The danger would be letting an international fight against terrorism devolve into a global clash between the West and Islam.
"It would be catastrophic to allow this to result in a clash of civilizations," says Strobe Talbott, former deputy secretary of state under President Clinton. "[To avoid that] it is essential the US define the coalition in an inclusive way [with] all parts of the civilized world. It must be remembered that many, many victims of this kind of terrorism have been Muslim."
Americans shouldn't expect to see creation of the kind of military coalition that Bush senior put together before attacking Iraq. According to analysts, this international alliance against terrorism is likely to work more on sharing intelligence and improving shared security measures. "When [Powell] uses 'coalition' he is talking about a sustained counter-terrorism operation, not preparing for a war in the sense of a military force," says Anthony Cordesman, a counter terrorism expert here.
Indeed, America's European allies appear to see this moment defining more than an international response to terrorism. The swift and unprecedented action taken by European leaders in NATO and the European Union indicates Europe sees the response to this "act of war" determining the future course of world affairs.
"There is this conviction that this was an act of such magnitude that it will be an epoch-making moment that will set the course of the kind of international system we will have for the next century," says Klaus Becher, a European security expert at the International Institute for Strategic Studies in London.
One reason NATO and the EU acted so resolutely, he adds, was "out of fear the US would be driven [by Tuesday's events] into the kind of unilateral attitude" that would set the post-cold-war era in a direction they don't want.
In that sense, the words out of Washington so far must be reassuring. While military action will likely be taken, Mr. Talbott says the stress on coalitions "is saying there are means other than the military that can be used."
Part of the US interest in securing a coalition is to help find its target and carry out measures against it. But "you need one kind of coalition against a country like Iraq, another against Osama bin Laden and Afghanistan," says Mr. Cordesman. "We need to be able to use the intelligence capabilities of our allies..."
The US clearly sees this as a moment defining "who is with us and who is against us" in fighting terrorism. Mr. Powell is emphasizing the contacts the administration is making with Pakistan, which has a muddled history of allying itself with the US while keeping warm ties to Afghanistan's Taliban government.
Eventually, experts see the crisis forcing the US to refocus on the Middle East. If Powell intends to get at what he called the "branch and root" of terrorism, the US will have to address the perception among a part of the Arab and Islamic world that the US talk of values translates into a two-tier system.
"The regional atmosphere is driven by the perception of American double standards," says Laura Drake, a Mideast specialist at American University. "The over-riding sentiment is that Palestinian and Iraqi human life is less valuable to Americans than their own, and the talk about civilization seems hypocritical to them."
The US-Arab rift certainly complicates the US effort to forge a coalition. "It's imperative we try to bring these countries aboard, but I'm not sure we can, at least very quickly," says Admiral William Crowe, former chairman of the Joint Chiefs of Staff.
Ann Scott Tyson contributed to this report.