US President Barack Obama's national security team met Saturday to weigh policy options after Russia's parliament endorsed military action in Ukraine, a White House official said.
Obama's team met at the White House to consider options and Defense Secretary Chuck Hagel earlier spoke by telephone with Russia's Defense Minister Sergei Shoigu, as Washington tried to keep pace with the fast escalating crisis in Ukraine and Crimea.
Senior members of the Washington national security establishment, including General Martin Dempsey, chairman of the Joint Chiefs of Staff, were earlier seen heading into the White House for the rare Saturday meeting.
"The president's national security team met today to receive an update on the situation in Ukraine and discuss potential policy options," a senior White House official said.
"We will provide further updates later this afternoon."
Obama was not in the meeting with the full team, but was briefed by his national security adviser Susan Rice and other senior officials as he mulled his options, according to the White House official.
Officials said there was "no change" to the US military's presence in the region.
The meetings came a day after Obama warned that there would be "costs" to Russia infringing the territorial integrity of Ukraine, following the ouster of pro-Moscow President Viktor Yanukovych.
That message was ignored by President Vladimir Putin, who asked Russian lawmakers for the green light to send troops into Ukraine, a move that prompted authorities in the ex-Soviet Republic to put troops on alert.
Ukraine's Defense Minister Igor Tenyukh earlier said that Russia had already sent 30 armored personnel carriers and 6,000 additional troops into Crimea to help pro-Kremlin militia gain broader independence from the new pro-EU leaders in Kiev.