THE United States is No. 1. There's just no doubt about it any longer. Look at the Vancouver summit: Two presidents met, and one asked the other for money. One of them leads a superpower. It isn't the one with the tin cup.
But where do we go from here? Seldom in modern history has one state stood above all others. There are few guides to the unipolar world.
Should the US try to prolong this preeminence, through maintenance of a large standing military, or other means? Can it? Does it matter?
One foreign policy expert says no. "The game is not worth the candle," argues Robert Jervis, the Adlai E. Stevenson professor of international politics at Columbia University.
Professor Jervis contributed an article to a section on "Primacy and its Discontents" to be published in a coming issue of the International Security journal. He says that geopolitics used to be all about striving to be first among equals. That's outmoded today, he says, because geopolitical posturing among great powers is no longer about war.
Nuclear weapons and the rise of liberal democracy in most developed countries, among other things, have made conventional war among powerful nations unlikely today, Jervis says. "If there isn't going to be a war, what does primacy mean?" he asks.
Sure, trade and economic disputes are still a problem. But spending billions on large military forces, say, isn't a good way to address those. "These are big issues because there are no real big issues in international politics," Jervis says.
It might be good for the US to experience working as an equal with other Western nations. "We've never done that. We've either been isolationist or the leader of the pack," Jervis says.
On the other hand, Christopher Layne of the University of California, Los Angeles, argues that US preeminence is but a moment in time, in any case. New great powers will inevitably rise, he says, such as Germany and Japan.
That's because other states inevitably feel threatened by a hegemony, he says, and take steps to protect themselves - whether that means forming a coalition with other states or building their own military power.
The few nation-states that found themselves at the top of the pinnacle before - such as France under Louis XIV and mid-19th-century Britain - found themselves equaled despite their best efforts, says Professor Layne, a visiting faculty member in international politics.
Ex-President Bush and others have said the US might be exempt from this phenomenon, because other nations trust the US to exercise power responsibly. Layne disagrees. "Other states don't have the luxury of relying on the good intentions of the dominant power," he says.
Layne says he thinks the US should not irk rivals by efforts to maintain its top status. Instead, it should let let them be contained by natural regional rivals. Germany, for instance, must worry about Russia; Japan, about China.
Harvard University's Samuel Huntington, on the other hand, argues that international primacy still matters. The US has strength and good intentions.
According to Professor Huntington, war among developed nations no longer seems likely. But he does not consider that a reason for the US to let down its guard.
"A world without US primacy will be a world with more violence and disorder and less democracy and economic growth," Huntington writes.