The White House says there's "overwhelming evidence" that Russia is fomenting unrest in eastern Ukraine.
However, President Barack Obama has not yet concluded that the actions warrant broader sanctions.
White House spokesman Jay Carney says the administration is "actively evaluating" how the U.S. should respond to the situation. He says the U.S. is also discussing that matter with international partners.
Carney suggests Obama could talk to Russia President Vladimir Putin as soon as today. They last spoke more than two weeks ago. Since then, pro-Russian forces have been on a rampage, storming and occupying local government offices, police stations and a small airport in eastern Ukraine.
Meanwhile, ousted Ukrainian President Viktor Yanukovych is accusing CIA Chief John Brennan of being behind Ukraine's decision to send troops into the east to quash the pro-Russian insurgency.
U.S. officials deny those accusations, but the White House has confirmed that Brennan visited the Ukrainian capital of Kiev over the weekend.
Are you worried about what's happening? Do these new developments make you think the U.S, should step in?