Days after his ally Viktor Yanukovich was ousted as Ukraine's leader, Russian President Vladimir Putin ordered a 150,000 troop Russian military exercise on Ukraine's border. The fall of Yanukovich - and Putin's potential response to it - has reignited a debate in Washington on how to respond to the assertive Russian leader.
For Obama administration officials, Vladimir Putin is a concern but not a threat. Any talk of renewed Cold War-like Russian-American rivalry, they say, is reckless and counterproductive.
"This is a world where we need to work with the Russians," a senior State Department official said on Tuesday. "This not about the United States versus Russia."
For Republicans, Mitt Romney's 2012 campaign declaration that Moscow was Washington's "number one geopolitical foe" is being proven correct. Now is the time, they say, to confront Putin.
"Romney's analysis of the Russian threat was actually spot on," said Nile Gardiner, a senior fellow at the Heritage Foundation and former Romney adviser. "That has been demonstrated amply over Ukraine, Syria and Russia as well."
Experts say Putin is still determined to include Ukraine in Russia's self-declared "sphere of influence." And he will continue to re-assert Moscow's place on the world stage by obstructing American diplomatic efforts in Syria, Iran and other countries.
"Putin's vision is not to restore the Soviet Union but to restore Russian greatness," said Kathryn Stoner, a Stanford University professor and expert on Russia. "It's the Russian empire, which is a very clear political and economic system."
Stoner called that system "Putinism" and described it as a complex mix of de facto authoritarianism at home and anti-American obstructionism abroad. It is by no means a Soviet-scale threat to the United States. But experts describe it as a controlling, culturally conservative system that Putin actively promotes to counter what he sees as a degenerate and decadent West.
"They're definitely setting themselves up in opposition to the United States," said Fiona Hill, an expert on Putin at the Brookings Institution in Washington. "Being the leaders of a conservative coalition of countries who oppose gay rights and gay marriage and those who want to see less of a role for the church, more of a secular society."
Gardiner, the former Romney adviser, criticized President Barack Obama for not expressing a Ronald Reagan-style message of "America advancing the cause of freedom" as a counterweight to Putin. He said an "ideological war" was underway and Putin is winning. Opponents of the United States are inspired by Putin, he said.
"Putin is viewed by American adversaries and competitors as someone who has stood up to American influence and gotten away with outflanking the United States," he said. "Adversaries take note of this and they sense weakness and that's dangerous. Dissidents also take note."
The senior State Department officials said there was no "point in making hollow threats" toward Moscow. In the wake of the wars in Iraq and Afghanistan, the American public has no interest in getting into a direct - or indirect - military confrontation with Russia in the Ukraine, Syria or virtually any other nation. The better option is to quietly work with Putin where possible behind the scenes.
"What we're trying to do is work through diplomatic channels with the Russians," said one senior State Department official. "That doesn't mean going public with some tough rhetoric that might please some domestic constituencies. This is not an era where tough talk gets the job done."
Publicly baiting Putin could prompt him to launch a military operation in Ukraine to defend Russian citizens as he did in Georgia in 2008.
At the same time, the United States and Europe must act urgently to aid Ukraine's spiraling economy. Interim government officials say that they will soon run out of funds to pay state workers, and the country will need a staggering $35 billion in aid in 2014 and 2015.
Yet the American and European response to the crisis has been ponderous, critics say. The main mechanism for providing aid to the country's new government is an International Monetary Fund loan program that would require punishing economic reforms, such as cutting long-running state subsidies that reduce average Ukrainians' energy costs. That step could prove highly unpopular.
Putin, in turn, had offered $15 billion in aid to Yanukovich before he fell. The Russian aid came with no obvious strings attached.
Stoner, the Stanford professor, said Putin may wait for Ukraine's new government and its Western backers to grow unpopular as they did after the country's 2004 Orange Revolution.
"The Russian idea of control is stepping back, watching what others do and then moving at the right time," she said. "We don't do that."
Hill, the author of a book about Putin, said the former Russian intelligence official has outmaneuvered Western leaders by waiting for the right moment and then acting forcefully when he sensed his adversaries were off-balance. She said Putin's grip on power was firm and Moscow would be a major player in regional dynamics from Europe to the Middle East for years to come.
"You can't ignore Russia," Hills said. "We just have to get smarter at playing this game."