U.S. President Barack Obama says he still hopes for a diplomatic solution to the crisis in Crimea, which will hold a referendum Sunday that could see it break away from Ukraine and join Russia.
Mr. Obama spoke to reporters in Washington Friday while meeting with Irish Prime Minister Enda Kenny ahead of the St. Patrick's Day holiday.
Meanwhile, Secretary of State John Kerry met in London with Russian Foreign Minister Sergei Lavrov to discuss the issue, but the talks appeared to end with little consensus.
Speaking to reporters following the meeting, Kerry reiterated that the United States believes the referendum in Crimea violates international law and the Ukrainian constitution, and that sanctions will be imposed on Russia if it is held. He said Russian approval of a vote favoring Crimea's unification with Russia would amount to "backdoor annexation" of the peninsula.
In a separate news conference after the talks, Lavrov said there is "no common vision" between the United States and Russia over the issue, but that the talks were "useful." He said Russia would "respect the will of the Crimean people."
Lavrov again criticized the sanctions that the United States and European Union are considering against Russia. He called sanctions "a counter-productive instrument" that "will not help mutual interests."
He also said Crimea means more to Russia than the Falkland Islands mean to Britain, which went to war with Argentina after it invaded the British overseas territory in 1982.
Also Friday, the Kremlin said Russian President Vladimir Putin told U.N. Secretary-General Ban Ki-moon in a phone conversation that the referendum in Crimea is "fully consistent with international law and the U.N. Charter."
On Thursday, Moscow acknowledged deploying thousands more troops and military hardware near the Ukrainian border for maneuvers that will continue for two weeks.
A senior State Department official said the U.S. is "very concerned" about the deployment, which adds to the 20,000 troops Kerry estimates Russia may have in Crimea.
The official said this is the second time in a month "that Russia has chosen to mass large amounts of force on short notice without much transparency around the eastern borders of Ukraine."
On Thursday, Ukraine's interim prime minister, Arseniy Yatsenyuk, confronted Russian Ambassador Vitaly Churkin at the U.N. Security Council, asking him bluntly whether "Russians want war."
Churkin replied that neither his government nor his people want war. He said, "I am convinced that Ukrainians don't want this either. We don't want any further exacerbation of the situation."
But U.S. and European leaders accuse Russia of interfering in Ukraine's internal affairs and have threatened Moscow with economic and diplomatic sanctions if Crimea leaves Ukraine.
Washington's U.N. ambassador, Samantha Power, addressing the Security Council Thursday, called for "a climate of restraint" and for "peaceful dialogue to replace [Russian] coercion."
She accused Russia of pursuing a course of military action "from the outset" of the crisis, which erupted in full in late February when pro-Russian President Viktor Yanukovych -- facing weeks of anti-government protests -- fled the country.
Earlier this week, as tensions mounted over the standoff, NATO announced its own deployment of fighter jets and surveillance aircraft in European territories bordering Russia.