"Stating the conflict in Ukraine was fueled by Russia, NATO said in a statement that the troop build-up had further escalated "a dangerous situation".
"We're not going to guess what's on Russia's mind, but we can see what Russia is doing on the ground – and that is of great concern. Russia has amassed around 20,000 combat-ready troops on Ukraine’s eastern border," NATO spokeswoman Oana Lungescu said in an emailed statement.
NATO was concerned that Moscow could use "the pretext of a humanitarian or peace-keeping mission as an excuse to send troops into Eastern Ukraine", she said.
seeing that the rebels are losing roads, cities and now even suburbs of Donetsk every day and that the tanks and the military material that was send last week didn't make any difference Putin has not many choices before him
remilitarizing the border and trying to provoke the Ukraine military in responding to the daily shelling of their territory and troops from Russia is one option, hoping that just as in Georgia he can find a pretext to go in (even if he has to invent shelling by Ukraine)
giving the troops the looks of a peaceforce and coming in to make a corridor while the humanitarian corridors in Ukraine are first agreed upon and immediately afterwards closed by the rebels is another possible reason
and so even if we have no war (yet) the tension in eastern europe is increasing again and everybody slowly starts getting nervous
and sends out warnings and starts mobilizing troops, activating procédures and sending or buying new and more arms
even if we don't have invasion, war we don't have peace either