THE HAGUE, Netherlands - With Moscow showing no signs of backing down from the standoff over Ukraine, President Obama today took a swing at Russian President Putin's status on the global stage - describing Russia as simply a "regional power."

"America's got a whole lot of challenges. Russia is a regional power that is threatening some of its immediate neighbors - not out of strength, but out of weakness," Obama said at a joint press conference with Dutch Prime Minister Mark Rutte.

Asked by ABC News if he now agrees with former political rival Mitt Romney's assertion that Russia is America's top geopolitical foe, Obama pushed back, saying: "Russia's actions are a problem. They don't pose the number one national security to the United States. I continue to be much more concerned when it comes to our security with the prospect of nuclear weapon going off in Manhattan."

"Ukraine has been a country in which Russia had enormous influence for decades - since the breakup of the Soviet Union. And you know, we have considerable influence on our neighbors. We generally don't need to invade them in order to have a strong cooperative relationship with them. The fact that Russia felt compelled to go in militarily and lay bare these violations of international law indicates less influence, not more," he added.

With roughly 30,000 Russian troops amassed on the border with Ukraine, Obama said the U.S. is "concerned about further encroachment by Russia into Ukraine."

"We oppose what appears to be an effort of intimidation, but Russia has a right, legally, to have its troops on its own soil. I don't think it's a done deal. And I think that Russia's still making a series of calculations," he said.

Obama stressed that the use of force would be a "bad choice" by Putin that would provoke further consequences from the international community, including sanctions against key sectors of the Russian economy.

"It has not just been my suggestion but it has also been the European Council's suggestion that should Russia go further, such sectoral sanctions would be appropriate - and that would include areas potentially like energy or finance or arms sales or trade that exists between Europe and the United States and Russia," Obama explained.

Obama reiterated that Crimea is not a "done deal" because the U.S. and its allies do not recognize the annexation of the peninsula. However, he conceded that "it would be dishonest to suggest that there's a simple solution to resolving what has already taken place in Crimea."

"The facts on the ground are that the Russian military controls Crimea. There are a number of individuals inside of Crimea that are supportive of that process. There's no expectation that they will be dislodged by force," he said. "What we can bring to bear are the legal arguments, the diplomatic arguments, the political pressure, the economic sanctions that are already in place, to try to make sure that there's a cost to that process."