What is the biggest challenge for new President?

Just hours after the Illinois Democratic senator completed a victory at the polls that was widely cheered around the world, another president thousands of miles away spoke up. He issued not the traditional, pro forma congratulations to an incoming American leader, but rather a blunt warning. Without citing Obama by name, Russian President Dmitry Medvedev vowed to place mobile missiles around the Russian enclave of Kaliningrad if the United States proceeds with deploying a controversial missile defense system in Poland and the Czech Republic.

Such a system—conceived and promoted by the Bush administration—would, in principle, be deployed during an Obama presidency. Obama has given broad support to missile defense if it were shown to be effective, but he has argued that the Bush administration has been rushing it toward deployment.

In any case, the Russian warning was a strikingly ungracious reminder that Obama will be inheriting a deeply troubled foreign policy legacy not of his making.

Meanwhile, Iran provided another reminder of unresolved tensions abroad. Military officials there announced that they would respond with force to any violation of Iran's airspace. Obama has expressed a willingness to have U.S. diplomats meet directly Iranian officials to discuss that country's nuclear programs, but hard-liners in Tehran are apparently nervous that a more fluid U.S. diplomatic approach to the issue could put them in a tough spot.

Still, the overwhelmingly warm international reaction to Obama's triumph signals that he will be able to tap into a reservoir of good will overseas that should assist his efforts to repair alliances. It should also help strengthen his hand in seeking extra help in dealing with a range of challenges—from the Taliban insurgency in Afghanistan to possible nuclear weapons break-outs to Middle East peace efforts, among others.

Obama's personal story and path-breaking rise to the presidency, coupled with his rejection of Bush's go-it-alone tendencies and the promise of change, are all primed to dampen the anti-Americanism that has plagued U.S. standing in the world during the Bush years. With an Obama presidency, says Kishore Mahbubani, a leading Asian foreign policy commentator and a former Singapore diplomat, "I personally believe...at least half of the anti-Americanism will vanish."

That could be a major soft-power asset, if Obama and his incoming diplomats can solidify and harness it to repair the damage to U.S. standing in the world.

Obama appealed to that soft-power sentiment on election night in remarks probably heard by more people overseas than in America. "Tonight we proved once more that the true strength of our nation comes not from the might of our arms or the scale of our wealth, but from the enduring power of our ideals—democracy, liberty, opportunity, and unyielding hope," he declared. "That's the true genius of America, that America can change."

But he paired that message with a warning of his own: "To those who would tear the world down, we will defeat you."

His running mate, Biden, told supporters that foreign challengers would find that Obama has "a spine of steel." The new president may well have an opportunity to demonstrate that quality in the months to come.

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