奥巴马为何对中国轮胎征税？一文从政治和经济层面上解读了近期奥巴马政府主导的中美贸易争端。那么，这一事件是否还有更深层次的原因呢？彼得森国际经济研究所主任弗雷德•伯格斯滕(Fred Bergsten)和高级研究员阿文德•萨勃拉曼尼亚( Arvind ubramanian)探讨了奥巴马政府在国家战略上的改变，向我们揭示：轮胎事件恐怕只是即将到来的中美贸易风暴的前奏。

     奥巴马(Obama)政府日益暗示，美国将不再继续担当全球最终消费国和进口国的角色。上月，白宫经济委员会主任拉里•萨默斯(Larry Summers)在彼得森国际经济研究所(Peterson Institute for International Economics)演讲和接受英国《金融时报》采访时，对此做了最清晰的表述。他表示，美国必须成为以出口为导向、而不是以消费为基础的经济体；必须依靠真正的工程技术，而不是金融“巫术”。美国财政部长蒂姆•盖特纳(Tim Geithner)和其它高官也发出了类似的、使美国经济增长恢复平衡的言论。

     美国采取新的姿态，不仅是出于经济方面的考虑，而且是出于战略方面的考虑。萨默斯此前已评述过美国的超级大国地位与净债务（外债）国身份之间的矛盾。如果美国依赖外国投资者纾困其金融业（就像本次危机初期时那样）、或者为其财政大幅扩张提供资金（就像中国和其它贸易顺差国长期所做的那样），美国的影响力可能就会大打折扣。美国无疑还认识到，今后可能无法再以可接受的价格为其庞大的贸易赤字融资，因此在某种程度上，美国此举也是迫不得已。

     要实现经济长期增长，美国就有必要加大出口，还可能需要减少经常账户赤字（目前约占美国国内生产总值(GDP)的3%）。美国还必须结束美元仍被高估的局面，尽管萨默斯没有（也不可能）这么说。彼得森国际经济研究所的威廉•克莱因(William Cline)和汤姆•威廉斯(John Williamson)所进行的研究表明，若想使美国的经常账户赤字接近上述目标所要求的水平，美元可能需要进一步真正的贬值——主要是相对人民币和其它亚洲国家的货币。

     短期而言，美国若想摆脱经济衰退实现复苏，财政和货币刺激计划必须奏效。反过来，这就要求国内外投资者平稳而放心地吸收美国政府发行的大规模债务。因此，至关重要的是：要避免让外界认为美元将要贬值（最起码不要让外界认为美元将大幅贬值），也不要给人以美国政府正推动美元贬值的印象。

     然而，一旦美国经济走出困境，萨默斯的长期结构性目标就将发挥作用。若想把资源从金融和消费转移到出口和投资，就需要调整相对价格，因此美元将不得不贬值。那么，现阶段较为强劲且承压能力更强的美元汇率，就可在复苏实现之后迅速协调好短期任务和中期目标。

     这一远景对美国的贸易伙伴国有何影响呢？从可信的角度来说，这是在向全球其它国家鸣枪警告。如果美国不再积欠持久的巨额经常账户赤字，那么中国（可能还包括德国和日本）等国就无法积累下持久的巨额经常账户盈余。它们也就无法依赖于出口导向型增长，从而必须寻找到持久和大幅扩大国内需求的办法。

     在减少全球失衡方面，已取得一些进展。美国经常账户赤字占GDP的比例已从逾6%的峰值水平降至3%左右。中国的经常账户盈余占本国GDP的比例已从11%降至9.8%左右，预计今年将继续下降。

     然而，我们无法保证这一过程会持续下去。克莱因预测，除非美国大幅削减预算赤字且美元大幅贬值，否则到2012年时，美国经常账户赤字占本国GDP 的比例将再次升至5%以上，随后还将飙升至空前水平。中国正在再次阻止人民币升值，至于它是否打算放弃重商主义的增长战略，目前尚未可知。

     当20国集团(G20)领导人今年9月齐聚匹兹堡时，列在议程首位的问题肯定是如何实现平衡且更高速的全球增长。美国在这一问题上的战略与其它国家的战略一致，至少目前如此。说的直白一点，萨默斯已经说过，中国不可能再像过去那样行事了，因为美国打算表现得更像中国。全球经济不允许两个（甚至一个半也不行）最重要的经济体都来实行中国式的增长战略。那么，哪个国家会胜出呢？
 

     英文原文
 

     The Obama administration is increasingly signalling that the US will not continue to be the world's consumer and importer of last resort. The clearest statements came last month from Larry Summers , White House economics director, in a speech at the Peterson Institute for International Economics and in an interview with the Financial Times. The US, he said, must become an export-oriented rather than a consumption-based economy and must rely on real engineering rather than financial wizardry. Tim Geithner, the US Treasury secretary, and other top officials have spoken similarly of rebalancing US growth.

     The logic of this new US position is not just economic. It is also strategic. Mr Summers has previously remarked on the tension between superpower status and net foreign indebtedness. US influence can be compromised if it is dependent on foreign investors to bail out its financial sector (as in the early part of this crisis) or to finance its fiscal profligacy (as China and other surplus countries have been doing for a long time). The US undoubtedly also recognises that it might not be able to finance large external deficits in the future at an acceptable price so to some extent it is making a virtue of necessity.

     This long-run vision for US growth entails greater exports and probably a smaller current account deficit than where it is now (about 3 per cent of gross domestic product). Although Mr Summers did not and could not say so, the vision will require an end to the remaining overvaluation of the dollar. Studies by William Cline and John Williamson at the Peterson Institute suggest that holding the US current account deficit to something close to these objectives will probably entail a further real depreciation of the dollar, mainly against the Chinese renminbi and other Asian currencies.

     In the short run, US recovery from the recession requires that the fiscal and monetary stimulus programmes be effective. In turn, that calls for domestic and foreign investors to absorb smoothly and trustingly the voluminous amounts of IOUs being offered by the US government. Hence it is essential to avoid perceptions that the dollar is about to fall, at least by very much, and that the US authorities are pushing it down.

     But Mr Summers' long-run structural targets will come into play once the economy is out of the woods. Redirecting resources away from finance and consumption towards exports and investment will require relative price shifts, for which the dollar has to move down. So a stronger rate for the dollar now and a more sustainable rate once the recovery has taken hold can reconcile the short-run imperative and the medium-term goal.

     What are the implications of this vision for America's trading partners? To the extent it is credible, it is a warning shot to the rest of the world. If the US will not run large and persistent current account deficits, countries such as China, and probably Germany and Japan, will not be able to run large and persistent current account surpluses. They will not be able to rely on export-led growth. They will have to find ways to expand domestic demand on a lasting and substantial basis.

     Progress is already being made in reducing global imbalances. The US current account deficit has come down from a peak of more than 6 per cent of GDP to about 3 per cent. China's current account surplus has declined from 11 per cent of GDP to about 9.8 per cent and is expected to decline much further this year.

     But there is no guarantee that this process will continue. Mr Cline predicts that the US current account deficit will rise back above 5 per cent by 2012 and soar into unprecedented terrain thereafter unless the budget deficit is cut sharply and the dollar depreciates substantially. China has again been preventing the renminbi from strengthening and the jury is still out on whether the country intends to depart from its mercantilist growth strategy.

     When the Group of 20 leaders meet in Pittsburgh in September, the question of how to achieve balanced as well as higher world growth must be at the top of the agenda. The US strategy on this issue is not, at least for the moment, consistent with strategies elsewhere. Put starkly, Mr Summers has stated that China can no longer behave like China because the US intends to behave much more like China. The world economy cannot have two, or even one-and-a-half, Chinese growth strategies from its two most important economies. Which will prevail?

     The writers are director and senior fellow of the Peterson Institute for International Economics