Please read Ukraine Crisis: Crimea Leader Appeals to Putin for Help at BBC New Europe.
"The unofficial pro-Moscow leader of Ukraine's autonomous Crimea region has asked Russian President Vladimir Putin for help to ensure peace.
"A Kremlin source said it would "not leave unnoticed" the request from Sergiy Aksyonov.
"Reports speak of a clash overnight in Crimea's capital and an attempt to seize a Ukrainian missile base.
"Ukraine's interim Prime Minister, Arseniy Yatsenyuk, accused Russia of seeking to provoke an escalation.
"Analysis Mark Lowen BBC News, Sevastopol There is still no official confirmation of who the armed men surrounding key areas in Crimea really are. They wear uniforms without insignia and drive unidentified vehicles.
"Some say they are locals organising themselves into a self-defence unit against the Ukrainian uprising. But many carry heavy weapons and appear in control of armoured personnel carriers. They seem more organised than an impromptu militia.
"And yet while Ukraine's government warns that Russia has carried out a "military occupation and invasion" of Crimea, it does not feel as though it has gone that far - yet. The cities are relatively calm and there is no sign of a mass armed uprising; just the ongoing control of key sites like airports and communications buildings.
"But this peninsula appears to be sliding steadily out of Kiev's control: the newly-elected Crimean prime minister now says all security and military forces here are under his command and his call to President Putin for direct help will not, says the Kremlin, be ignored. As the new Ukrainian cabinet meets, how to extend its writ here will be the urgent priority.
"He was speaking at the first meeting of his cabinet, installed after the overthrow of President Viktor Yanukovych. New Defence Minister Ihor Tenyukh accused Russia of "recently" deploying 6,000 extra soldiers to Ukraine.
"US President Barack Obama warned Moscow against any military intervention as unidentified soldiers, thought to be Russian, fanned out in the south of the peninsula, surrounding airports and communications centres.
"According to Mr Aksyonov, soldiers from Russia's Black Sea Fleet based in Crimea are helping to guard strategic buildings. But the fleet's press service only told a Russian news agency Ria-Novosti it would help guard fleet installations.
"Under the agreement governing the presence of the fleet in Crimea, the Russians must co-ordinate all troop movements outside the fleet's base areas with the Ukrainian authorities beforehand."