What about the United States，the true hyper-power of our area？For this country，the case for multilateralism is no less compelling，though it is more subtle.Of course，this country"s leaders must look after national interests；in deciding how to interact with the rest of the world，any government must put national interests before global altruism.Perhaps this is why some influential people are tempted to believe that，to protect its national interests，all the United States need do is to exert its unmatched military and economic power-and no matter if that implies sidelining the multilateral system.
I dare to dissent with this view，however，not only because it can lead to unwarranted adverse consequence for other countries，including my own，but also as a friend I want to suggest that unilateralism may actually undermine the interests of the United States itself.
The fundamental flaw of the unilateralist way of thinking is to ignore how interdependent all countries-the United States among them-have become，for better or for worse.True，the rest of the world depends perceptibly on what the U.S.does or does not do，but the converse is also true.The world in our time may beunipolar，but it is interdependent，too.
At this hour of global interdependence，even the mightiest power has limits to its inf luence，to its capacity to control how others react to its actions.For unipolarity to be more than a moment in history，other must perceive it not as a threat but as a true anchor of peace.Peaceful and lasting unipolarity depends on the multilateralsystem-as much as the multilateral system depends on the enlightened，not the aggressive，leadership of the sole hyper-power.Aggressive unipolarity sooner rather than later world set the world in search of a different equilibrium，one in which the military power of the United States could be balanced.This process would prove expensive and tragic.A world with so much poverty cannot afford another arms race.A world that has made so much progress in embracing the values of democracy deserves better than to relapse into threats of mutual destruction.
Further，the United States is not exempted，even by the sheer force of its power，from problems that inexorabby call for inter nationally coordinated responses.
Consider for a moment the biggest security concern of this and many other nations：transnational terrorism.It would be dangerously nave to think that terrorism can be fought single handedly.Can terrorists be defeated without international cooperation？Can the international traffic in deadly weapons，or the spread of fanaticism，be stopped if countries do not work together？Never.Combating terrorism requires the support of friends，allies，sometimes even adversaries.To achieve security，military might is not all that counts.
International cooperation advances not only the security but also the military superiority of the United States.It would be cynical not to believe that the multilateral instruments，including the Nuclear Non-proliferation Treaty，adopted to prevent the spread of weapons of mass destruction in fact help to entrench the overwhelming military advantage of the United States.
Other than security there are many problems，faced by the United States and all countries that respect no national boundaries and therefore require global cooperative solutions.Think of global warming，destruction of biodiversity，fisheries depletion，ocean pollution，infectious diseases，drug trafficking，or human smuggling，just to name a few.Not one of these dire challenges can be met by a nation acting alone.Only through international cooperation can there be any hope of success.
Equally，in the pursuit of prosperity and the prevention of evils such as international financial crises，recessions，and how def lation，international cooperation is vital to success.Economic cooperation is needed now more than ever.There is a danger that the multilateral trading system could become the battleground of unsettled geopolitical disputes，with disastrous consequences.This danger haunts the ongoing WTO Doha round of trade liberalization-now practically at gridlock-and fuels numerous trade disputes between old partners.The Doha round must be saved and the neo-protectionist spiral must be checker right now；any later may be too late.International cooperation is also needed to tackle in a coordinated fashion the very serious macroeconomic imbalances afflicting all the major economies of the world.Failure to coordinate will make the unavoidable adjustment more painful，andcould eventually cause a major headache in the international economy.
