@revelette2,
Of course Ukraine has mobilised it's troops. So far there's been a lot of posturing, let's hope it doesn't go beyond that.
Neither side is stupid enough to use nukes, that's completely ridiculous. Ukraine was never going to join NATO.
Putin failed diplomatically by pressuring Yanukovych into not signing the deal with the EU. It backfired, he completely miscalculated, and now to save face he's going to try the military option. On Channel 4 News a Russian spokesman blamed western meddling in Ukrainian affairs which forced Russia to intervene. Then he started going on about Iraq. Russia has declared a humanitarian crisis in Crimea, but there's absolutely no evidence of one, no refugees, clear roads etc.
When the Russians feel they've done enough to save face they'll sit down and talk, that is if nothing goes wrong, which it quite easily could.