LONDON -- An eleventh-hour U.S. effort to resolve the growing confrontation with Russia over Ukraine failed Friday, and Moscow shipped more troops and armor into the flash-point Crimea region ahead of a planned vote on breaking away from Ukraine and rejoining Russia.
Secretary of State John Kerry warned against a "backdoor annexation" by Russia of the strategic Black Sea peninsula. But Mr. Kerry conceded that six hours of London talks with Russia's top diplomat neither stopped Sunday's vote nor opened a new diplomatic path for Moscow to step back from the Cold War-tinged standoff.
The most significant U.S. and European sanctions against Russia since the collapse of the Soviet Union appeared all but certain.
"We don't have a common vision of the situation," Russian Foreign Minister Sergei Lavrov said after the crisis talks.
No agreements were reached, Mr. Lavrov told reporters. He stressed that Russia insists on Crimea's right to hold the referendum. He said Russia would decide after the vote on how to respond. Pressed about whether Russia would annex Crimea after the vote, he said, "There are no what-ifs in politics."
Voters in Crimea will decide whether to secede from Ukraine and join Russia or remain part of Ukraine with greater autonomy. The vote will be held under the eyes of Russian troops, who effectively took control of Crimea late last month after protesters overthrew the Ukrainian government. The Crimean regional parliament has already voted to leave Ukraine, and the traditionally pro-Russian population of Crimea is expected to approve the idea as well.
Moscow's tightening grip on Crimea and the gathering of Russian troops along the two countries' border have unnerved Ukrainians and left the country's fledgling government concerned about further Russian military action. Mr. Kerry said the United States was "deeply concerned" about those deployments.
The United States and other nations have been dangling a diplomatic solution for Russia, tacitly acknowledging that the referendum would produce a pro-Russia outcome while suggesting that Russia could avert further escalation by leaving Crimea's precise status vague.
But Mr. Kerry said Mr. Lavrov had made clear that Russian President Vladimir Putin was not prepared to take that step. Mr. Lavrov said Russia will "respect" the results of the plebiscite, and it was apparent from Mr. Kerry's tone that the United States fears full annexation.
"We did not find common ground today on the way ahead," said a senior U.S. official who spoke on condition of anonymity to describe the roughly six hours of intensive discussions Friday.
The European Union is expected to impose travel bans and asset freezes Monday on Russians accused of complicity in Moscow's military incursion and the intimidation of Crimea. The EU on Friday identified more than 120 such individuals.