At the same time , on the road toward Slaviansk , CNN 's Phil Black encountered a heavily fortified and well organized police checkpoint and saw signs of a large military buildup . Obama says Ukraine will face new challenges . NATO chief announces ` ` further military intervention to reinforce our collective security '' Conflicting reports on Ukrainian soldiers switching sides . Russian President Vladimir Putin says Ukraine is ` ` on the brink of civil war ''
Obama says Ukraine will face new challenges . NATO chief announces ` ` further military intervention to reinforce our collective security '' Conflicting reports on Ukrainian soldiers switching sides . Russian President Vladimir Putin says Ukraine is ` ` on the brink of civil war ''