U.S. President Barack Obama conducts foreign policy in a manner that is deliberate, careful and pragmatic. He shuns grand theories and readily acknowledges the limits of American power.
Now he is facing off against an adversary who displays none of those characteristics: an authoritarian leader who has a certainty about Russia's place in the world and no qualms about using force to counter a perceived threat.
The crisis in Ukraine means that those two different world views and personalities are on a collision course. For Mr. Obama, the challenge is to rally the international community behind measures aimed at punishing Russia's Vladimir Putin for his incursion into Ukrainian territory – and to deter him from venturing any farther.
The contours of what such steps might look like became clearer on Monday. The United States is readying a slate of economic sanctions, according to a spokesperson for the State Department. The North Atlantic Treaty Organization is holding an extraordinary meeting on Tuesday where it will consider bulking up its forces in countries bordering Ukraine. And there are moves under way to isolate Russia diplomatically, including possible expulsion from the Group of 8 major industrialized nations.
Mr. Obama reiterated that Russia's recent actions carry a price. "Over time this will be a costly proposition for Russia," he told reporters on Monday before a meeting with Israeli Prime Minister Benjamin Netanyahu. "Now is the time for them to consider whether they can serve their interests in a way that resorts to diplomacy as opposed to force."
The coming days will determine whether the international community bands together in response to the Russian seizure of Crimea. "This is one of the largest tests we've faced in a very long time," perhaps since the Iraqi invasion of Kuwait, said Ivo Daalder, who served as the U.S. representative to NATO until last year and is now president of the Chicago Council on Global Affairs. "It is a test for the United States and for Barack Obama. But it really is a test to everyone, to the fundamental nature of our order."
Mr. Obama "has made it a point of policy that the United States will do less military intervention and more diplomatic intervention," said Kevin Ryan, a retired U.S. Army brigadier-general and scholar at Harvard University who previously served as a defence attaché at the U.S. embassy in Moscow. "Here is a big test of that policy. Can that be successful?"
Unlike Mr. Putin, Mr. Obama has to contend with vocal critics within his own legislature. On Monday, Republican Senator John McCain said the situation in Ukraine was "the ultimate result of a feckless foreign policy in which nobody believes in America's strength any more."
Speaking to a pro-Israel lobby group, Mr. McCain – who unsuccessfully challenged Mr. Obama for the presidency in 2008 – said Mr. Obama had misjudged Mr. Putin. "The President of the United States believes the Cold War is over. That's fine, it's over. But Putin doesn't believe it's over," Mr. McCain said.
Yet even critics like Mr. McCain acknowledge that there is no workable military response by the U.S. to the current situation. The closest thing to a show of force could come on Tuesday, when NATO meets in response to a formal request by Poland, which invoked a rule whereby any member of the alliance can call for talks if it considers its security under threat.
Those consultations could result in the redeployment of forces into Eastern Europe "to underscore that we take NATO seriously and to remind Russia that we too have options," Mr. Daalder said.
There is also a race under way to reach agreement on a menu of measures to cause economic pain to Russia and its ruling elite. Such steps could include sanctions, the freezing of assets in bank accounts outside Russia, travel bans and trade restrictions.
On Monday, the United Nations Security Council met on Monday for the third time since Friday. Russia has veto power on the council, so the group is highly unlikely to authorize any action in response to the situation in Ukraine. But diplomats were unsparing in their criticism. "There is nothing that justifies Russian conduct," said Samantha Power, the U.S. ambassador, at the meeting. "It is an act of aggression. It must stop."
The U.S. and its allies are racing to reassess their approach to Russia. "We're beginning to build a different framework for our policy," Mr. Ryan said. The idea "that we could reset or have this friendly relationship has been killed."
Judging by his track record, Mr. Obama will be above all pragmatic and realistic in what the U.S. can achieve. Although he favours diplomacy, he is no peacenik. He has made extensive use of drone strikes in Pakistan and Afghanistan and pushed ahead with a military intervention in Libya. When he was awarded the Nobel Peace Prize in 2009, he used his acceptance speech to underline that the use of force is sometimes necessary.
In a crisis, he relies on his close advisers but also keeps his own counsel. His kitchen cabinet in matters of foreign policy is varied: It includes Susan Rice, the current national security adviser, and Ms. Power, the UN ambassador, both of whom are associated with a more idealistic, interventionist strain of foreign policy. But it has also included a trio of senior counsellors that Mr. Obama nicknamed "the grim Irishmen," according to a recent profile in Politico magazine, all known for their clear-eyed realism.
Mr. Obama's case-by-case approach to foreign policy predicaments – intervening to prevent bloodshed in Libya, for instance, but allowing Syria to descend into civil war – has led critics to call him indecisive and inconsistent.
For now, the President isn't deviating from the measured approach that is his hallmark. As he told an interviewer in 2011, "When you start applying blanket policies on the complexities of the current world situation, you're going to get yourself into trouble."