U.S. Secretary of State John Kerry says Russian acceptance of a Crimean referendum to break off from Ukraine and possibly join Russia would be an illegal "backdoor annexation."
Kerry met with Russian Foreign Minister Sergei Lavrov for six hours in London Friday in another effort to defuse the tensions in Crimea.
If Sunday's vote passes and the Russian parliament ratifies it, Kerry said that would violate international law. He said it would fly in the face of every legitimate effort to find another way to protect the interests of Russia and Crimeans while respecting Ukraine's sovereignty.
Kerry said there will be consequences. He says this is not a threat against Russia but a matter of respecting international standards for annexation and independence.
Lavrov said in a separate news conference that the talks with Kerry were useful, but the two have "no common vision" on Crimea. He said Russia will "respect the will of the Crimean people," and he criticized the threat of U.S. and EU sanctions on Russia as "counterproductive."
President Barack Obama said Friday he still hopes for a diplomatic solution to the crisis in Crimea. But Secretary of State Kerry said it is clear Russian President Vladimir Putin will not make any moves until after Sunday's referendum.
The Kremlin says Mr. Putin told U.N. Secretary-General Ban Ki-moon in a phone call that the referendum is "fully consistent with international law and the U.N. Charter."
Moscow acknowledged Thursday that it is deploying thousands more troops and military hardware near the Ukrainian border for two weeks of military maneuvers.
The State Department says it is "very concerned" about the deployment. The U.S. estimates that Russia already may have 20,000 troops in Crimea.