A senior Obama administration official said Russia has complete control of Crimea and that there are more than 6,000 airborne and naval forces in the peninsula.

“Russian forces now have complete operational control of the Crimean peninsula, some 6,000-plus airborne and naval forces, with considerable materiel,” the official said in a briefing for reporters. “There is no question that they are in an occupation position in Crimea…”

He also said Russia was flying in reinforcements. 

From The Guardian live blog:

The officials told a conference call with reporters that there had also been “occasional ethnic skirmishes in parts of the east” of Ukraine, and that there was particular concern about the north-eastern city of Kharkiv, where “efforts to stir up ethnic Russians” against Kiev had been detected.

“We are concerned as we watch this situation that the Russians have badly miscalculated,” one senior official said. “There is a very fierce and proud tradition in Ukraine of defending their sovereignty and territorial integrity.”

“So far Ukraine has showed, and Ukrainians individually have showed, marked restraint… but the longer this situation goes on, the more delicate it becomes.”

Officials said Kerry would travel to Kiev on Tuesday to meet the interim Ukrainian government and discuss American support.

Plans for a trip to Moscow by the US trade representative and a visit by Russian officials on energy cooperation have both been cancelled.

Gunmen and Russian soldiers surrounded two Ukraine military bases in Crimea Sunday. PZ News feed is tweeting out reports of two loud explosions in Simferopol and that Russians are taking ammunition stores in Sevastopol, an important port city.