Russian President Vladimir Putin on Saturday ignored U.S. warnings to stay of Ukraine, asking for and receiving authority from his parliament to use military forces in Ukraine’s strategic region of Crimea.

A resolution allowing force was approved by the Russian legislature’s upper house, and Mr. Putin said such a move is necessary to protect ethnic Russians and military bases in Crimea. The region is home to a large ethnic Russian population and has become the stage on which Mr. Putin seeks to exert control and influence over the region.

“I’m submitting a request for using the armed forces of the Russian Federation on the territory of Ukraine, pending the normalization of the socio-political situation in that country,” the Russian president said in a statement released by the Kremlin.

While the resolution appears meant to address the situation in Crimea — where the region’s regional prime minister earlier this week asked Russia for help — the fact that it refers more generally to “the territory of Ukraine” leaves open the possibility Russia could send its military into other parts of the troubled nation.

The Russian moves come less than 24 hours after the White House delivered a stern warning to Mr. Putin, with President Obama personally vowing “there will be costs” if Russia continues its aggressive posture.