The United States and Russia failed Friday to resolve a Cold-War-style standoff sparked by Moscow's military intervention in Crimea, as the clock ticks down to the region's vote on splitting from Ukraine.
A member of the Crimean Tatar community waves the Ukrainian national flag during a pro-Ukrainian demonstration near the village of Ilinka on March 14, 2014
US Secretary of State John Kerry flew in early Friday for whirlwind talks with Russian Foreign Minister Sergei Lavrov in London, with few illusions that Sunday's Moscow-backed referendum in the strategic Black Sea peninsula could be averted or delayed.
But US hopes of at least winning assurances from Lavrov that Russian President Vladimir Putin would not move swiftly to annex Crimea and that Russian troops would be pulled back to their barracks were broadly dashed.
Kerry found himself at check-mate when Lavrov "made it clear that President Putin is not prepared to make any decision regarding Ukraine until after the referendum on Sunday", the top US diplomat told reporters.
While Washington still hopes Moscow will not take the extra step of actually annexing the Crimea region of two million mostly Russian speakers, officials admitted they were now in a nail-biting wait-and-see mode.
Kerry also warned against the Russian parliament or Duma ratifying Sunday's vote which he said would amount to a "backdoor ratification" -- a move that would trigger sanctions and escalate the biggest East-West showdown since the 1989 fall of the Berlin Wall.
- 'No common vision'-
Despite six hours of talks, including two long tete-a-tete walks in the grounds of the lavish US ambassador's residence in central London, Lavrov said Russia and the West remained far apart on Ukraine.
"We have no common vision of the situation," said Lavrov.
And he hinted that Moscow was now resolved to bring Crimea under its eventual control.
"Everyone understands -- and I say this with all responsibility -- what Crimea means to Russia, and that it means immeasurably more than the Comoros (archipelago) for France or the Falklands for Britain."
Kerry again warned the international community would not recognise the results of the referendum and said if it goes ahead "there will be some sanctions, here will be some response".
British Foreign Secretary William Hague said the failure of the talks was "deeply disappointing" and called for "tougher restrictive measures."
Asked when the United States would respond to the referendum, White House spokesman Jay Carney said: "I think, without putting too fine a point on it, I'd say quickly."
Kerry insisted again that Washington did not want to impose sanctions on Moscow, but said even just the threat was causing Moscow stocks to tumble.
They plunged to a four-year low Friday as jittery investors dumped their holdings ahead of the referendum, while the ruble again fell against major currencies.
US stocks also took a hit while oil prices rose.
- World leaders to up pressure -
NATO head Anders Fogh Rasmussen urged Moscow to act responsibly, saying the "so-called referendum... would undermine international efforts to find a peaceful and political solution".
Russia "should act responsibly, uphold its obligations under international law", he said, adding negotiations should be given a chance.
Kerry was now due to head home Saturday for further consultations with the White House, with world leaders likely to step up pressure in the final hours before Sunday's vote.
UN Secretary General Ban Ki-moon called Putin Friday and afterwards said he still thought a negotiated solution was possible, although it was "clear we are at a crossroads".
The UN Security Council was to vote Saturday on a resolution on Ukraine.
"The only objective of a resolution would be to get the Chinese to abstain and isolate Russia further," a council diplomat said.
The former Soviet republic of some 46 million people remained a tinderbox as more than 8,000 Russian troops staged drills near its eastern border while NATO and US reconnaissance aircraft and fighters patrolled the skies of its EU neighbours to the west.
Despite US alarm over the Russian military build-up along Ukraine's eastern borders, Lavrov said Moscow "has no, and cannot have, any plans to invade the southeast region of Ukraine" where Russian speakers mostly reside.
Russia still refuses to recognise the legitimacy of the Western-leaning team that has taken power in Kiev -- a move that threatens to shatter Putin's dream of rebuilding an empire dominated by Moscow.
Deadly violence returned this week to Ukraine for the first time since nearly 90 people were killed in a week of carnage before the fall of the pro-Moscow regime as a pro-Kiev protester was stabbed to death in the mostly Russian-speaking eastern city of Donetsk.
Sunday's vote gives residents of Crimea -- a rugged region that has housed tsarist and Kremlin navies since the 18th century -- only two choices: joining Russia or "the significant strengthening of their autonomy within Ukraine".
The peninsula's self-declared leaders have already predicted an easy victory and the region is largely expected to vote in favour of joining Russia despite discontent from the Muslim Tatar minority that makes up 12 percent of Crimea's total population of two million.
Around 500 Crimean Tatars took to the streets of their main settlement on the region after prayers on Islam's holy day to protest the "illegal" referendum and call for a boycott.
The European Union will debate travel bans and asset freezes on Monday against some 30 Russian and Ukrainian officials held responsible for threatening Ukraine's territorial integrity.
A Russian state arms and technology group, Rostec, said meanwhile that it had intercepted a US surveillance drone above Crimea flying at about 4,000 metres (12,000 feet).