President Obama threatened Moscow with expanded global sanctions Tuesday, calling Russia a less-than-lofty “regional power” that poses less of a threat to the United States than a lone terrorist operating in New York City.

Obama’s dissection of the “problem” Russia poses to its neighbors and the rest of the world was his clearest public effort to date to cast President Vladimir Putin as a politician frustrated by his nation’s diminished global influence. That frustration has prompted, Obama said, Putin’s nonsensical justifications for annexing Ukraine in a display of opportunistic brawn.

During a news conference at the conclusion of an international nuclear summit in the Netherlands, the president cast the Russian leader as something of a nuisance to the United States more than a worrisome national security hazard.

Asked by a reporter to respond to Mitt Romney’s assertion that Russia is America’s most important geopolitical threat, Obama said he disagreed. Russia is not “the No. 1 national security threat,” he countered. “I continue to be much more concerned, when it comes to our security, with the prospect of a nuclear weapon going off in Manhattan.”

In collaboration with U.S. allies, Obama needled Putin by repeating that Russia’s march into Ukraine’s Crimean peninsula is viewed in world capitals as a sign of Moscow’s weakness. On Monday, the countries that make up the Group of Seven leading economies expelled Russia from G-8 membership because of the country’s aggressive actions in Ukraine.

“Russia is a regional power that is threatening some of its immediate neighbors -- not out of strength, but out of weakness,” the president said. By invading Ukraine after decades of friction, “the fact that Russia felt compelled to go in militarily and lay bare these violations of international law indicates less influence, not more,” he said.

The president also sought to downplay Europe’s clear reluctance to impose energy and financial sanctions as punishment for the annexation -- hesitation that underscored Europe’s fears that Russia wields economic power as an energy supplier.

Obama conceded that Crimea, now absorbed by the Russian Federation, may not be legally recognized as Russian territory by the world’s cartographers but is unlikely to return to Ukraine’s governance anytime soon. The president tacitly established as a trigger for possible new international sanctions the invasion of Eastern Ukraine, along the border of which thousands of Russian troops are now massed.

While the United States would not militarily defend Ukraine against invading forces, America will abide by agreements to defend neighboring NATO countries against any Russian advances, Obama repeated.

On Wednesday, he will meet with NATO leaders in Brussels and participate in a U.S.-European Union summit at which Ukraine and Russia will remain in the spotlight. Obama will deliver a speech that aides said will underscore the importance of the international "system" the United States and Europe created to ensure security, aimed at breaches of international law and democratic values visible most recently in Russia's actions in Ukraine.

Obama defended his administration’s foreign policy aims in the broadest sense Tuesday, as well as America’s ability to be a global defender of principles in ways that change outcomes, even without direct involvement of U.S. troops.

“The truth of the matter is the world has always been messy,” he said. “And what the United States has consistently been able to do, and we continue to be able to do, is to mobilize the international community around a set of principles and norms. And where our own self-defense may not be involved, we may not act militarily. That does not mean that we don't steadily push against those forces that would violate those principles and ideals.”

Accompanied by Prime Minister Mark Rutte of the Netherlands, Obama expanded on National Security Agency spying in the United States and abroad, a subject that challenges international trust and alliances following revelations about the NSA by former contractor Edward Snowden.

The White House anticipated questions from U.S. and international reporters Tuesday after the administration disclosed to The New York Times that Obama would ask Congress to shift metadata storage practices from government spy agencies to private telephone companies, under judicial supervision.

When independent stakeholders proposed last year that Obama order a similar overhaul administratively, he agreed to end the government’s metadata retention for five years or longer, but said resistance from the phone companies to accepting new custodial responsibilities rendered the option unworkable. On Tuesday, he expressed a contrary view, arguing that if the phone companies retained Americans’ call records for a shorter period, the change should satisfy all concerned.

The president urged Congress to send him legislation that would end the NSA’s bulk metadata collection and retention by shifting the responsibility to phone companies for a data-preservation period of 18 months.

Nonetheless, it is no secret that prospects for passage during an election year, especially among Democratic senators who are at odds with Obama over the intelligence community’s activities, remain unlikely this year and perhaps a non-starter for the remainder of the president’s term. Without changes from Congress or the executive branch, current spy practices aimed at catching terrorists will continue unless barred by the courts.

“I'm confident that it allows us to do what is necessary in order to deal with the dangers of a terrorist attack, but does so in a way that addresses some of the concerns that people had raised,” Obama said. “I'm looking forward to working with Congress to make sure we go ahead and pass the enabling legislation quickly, so that we can get on with the business of effective law enforcement.”