Ukraine's acting prime minister is "convinced" that Russia's military won't intervene in his country—but Ukraine's military is prepared for action. If Moscow were to make such a move, "this would be the beginning of war and the end of all relations," says acting PM Arseniy Yatsenyuk, per the BBC. Indeed, a Ukrainian military official says soldiers are cleared to "open fire" if attacked, the New York Times reports. "We perceive Russia's actions as direct aggression towards the sovereignty of Ukraine," tweeted acting president Oleksandr Turchynov.
According to the Times, Russia has "effectively seized control" of the Crimean Peninsula, and Ukraine's UN ambassador says 15,000 Russian troops are in the region, per a CNN tweet. In a cabinet meeting, however, Yatsenyuk referred to Russia's stance as "nothing but a provocation," CNN reports. "Ukraine will not be provoked. We will not use force. We demand that the government of the Russian Federation immediately withdraw its troops." Meanwhile, John McCain is calling on President Obama to respond: The president should "make clear what costs Russia will face for its aggression and ... impose those consequences without further delay." (Read more Arseniy Yatsenyuk stories.)