As the G-Plenty and Not-so-Plenty meet in Cannes a big month beckons for the United States. One month hence will be the seventieth anniversary of Pearl Harbor which brought a formal and abrupt end to 1930s American isolationism. December 2011 will also see the withdrawal of US combat forces from Iraq. One year hence the US presidential elections will take place. Obama’s first term has been dominated by extracting America from Afghanistan and Iraq and NOT dealing with debt and financial disaster. Obama’s second-term (the presidential candidates on the US Right are hopelessly split and/or less than compelling) will face déjà vu all over again; how to deal with a break-out WMD state in the Middle East. The way in which Washington deals with the coming Iranian Crisis will do much to set American grand strategy on its twenty-first century course.

The International Atomic Energy Authority’s (IAEA) is about to issue a report that Iran is speeding up efforts to enrich weapons-grade uranium. This will lead to crisis with Israel. It is thus strategic make your mind up time for America – continue as a somewhat less super-power in a constrained leadership role or join its feckless and hopeless European allies in a) global isolationism; and b) selling the family silverware to the dodgy dealers over the horizon to pay for debt obesity.

Strategy is the preserve of the relatively weak. Ten years ago there were a few in Washington (an influential few) who were mad enough to believe that America the Mighty was so strong that strategy need simply be a shopping list of America’s wants in the world. And, whilst Twain-esque reports of America’s strategic demise are hopelessly premature the United States today looks like Britain in 1911 – immensely strong on paper and yet spread thin the world over.

America has been a liberating power, but one that has always and rightly had a keen sense of the national interest. Since 1945 that power has been sustained by a strong sense of internationalism, more often than not supported by European allies the freedom from tyranny of which the US has been the ultimate guarantor. American internationalism has also been sustained by clear economic benefits for the American people. However, something profound has changed that is evident at Cannes; the globalisation which emerged from American free market internationalism is no longer working overwhelmingly in America’s favour.

Furthermore, since 911 American prestige has badly been damaged by two inconclusive wars in Afghanistan and Iraq. Although nothing like as costly as World War Two or the Vietnam War this loss of prestige has enabled China to turn economic strength into political influence. Beijing is now on the way to becoming the new peer competitor of America in a new bipolar world. Taken together globalisation and China’s emergence on the crest of an economic bow-wave faces Washington with the most profound of strategic choices; retreat back into a form of neo-isolationism or re-commit to a new form of leadership.

The latter option begs a question; leadership of what? By now Europe should have joined the US in a form of bipolar leadership of the West in the world. Instead, Europe is retreating ever deeper into Euro-isolationism as Germany and France seek ever more incompetent ways not to deal with the Eurozone crisis. Britain? America’s hitherto ‘special relation’ has become a very little ‘power’ retreating from influence both in Europe and the wider world with a fractured society trapped in self-defeating political correctness. What price Europe for the continued commitment of America to Europe’s stability? Japan is a possible partner but is recovering from an enormous natural disaster and twenty years of stagflation. India is being India – non-aligned.

American strategic leadership will thus be far more complex than hitherto making decisive action against Iran very dangerous. Power-shift is the elephant in the room at Cannes. Like it or not the centre of gravity of future American power will be the Asia-Pacific region with the US cast as great stabiliser. Challenges will be for the mostpart indirect with new and old technologies used to offset American power, often in league with non-state actors, such as Al Qaeda – be it cyber-attack or WMD proliferation. And, the Middle East will continue to boil as the Arab Spring creates as many autocrats as democrats.

Faced with such complexity American leadership could well be an oxymoron with the role of traditional diplomacy ever more important, with coalitions rather than formal alliances being the stuff of American foreign and security policy. This will in turn require a big shift in the balance between American diplomacy and force. That will be a difficult call for any future American president to make. Political culture, deficit-reduction and pork barrel politics all tend to undermine American soft power. The iron triangle of political funding, defence industries and the armed forces still exerts undue influence in Washington fifty-one years after President Eisenhower warned about the military-industrial complex.

It was Winston Churchill who said that, “You can always count on Americans to do the right thing – after they’ve tried everything else.” Let us hope so. For over sixty years American leaders have more or less ignored Jefferson’s famous dictum to avoid entangling alliances. If America is ever going to heed Jefferson’s warning now is the deficit-ridden, withdrawal moment it is going to happen. Iran will prove the test – pre-empt an Iranian bomb by attacking it; build a political coalition that somehow prevails upon Tehran or simply live with the Iranian bomb and constrain a frightened Israel.

Tough call.

Julian Lindley-French is Eisenhower Professor of Defence Strategy at the Netherlands Defence Academy, Fellow of Respublica in London, Associate Fellow of the Austrian Institute for European and Security Studies and a member of the Strategic Advisory Group of the Atlantic Council. He is also a member of the Academic Advisory Board of the NATO Defence College in Rome. This essay first appeared on his personal blog, Lindley-French’s Blog Blast.