has called on president putin to send russian troops as peacemakers. vice-president joe biden landed in kiev today to meet with ukrainian officials. he is set to talk with the acting prime minister and president in ukraine tomorrow. meantime, those pro russian militants in the east are calling for a referendum to join russia, following the lead of separatists in crimea. let's get to steven piper, former u.s. ambassador to ukraine. now the director of the arms control and nonproliferation institute at the brookings institution. thank you. >> happy to be here. >> not at all a surprise russia is pulling the strings here. i'm surprised they got caught red-handed, to the. >> i think there's been a lot of evidence over the last two weeks that these takeovers in the ten towns in eastern ukraine were orchestrated by the russian military, by russian special services and some cases looks like there's stunning evidence. >> now the question is, what