But if America were stronger and more decisive, a country like Russia would be more likely to think twice and hold off. Under the circumstances, however, Putin knows perfectly well that Obama will do nothing -- so why wouldn't Putin invade Ukraine??
This isn't an Obama thing. Remember Russia invaded South Ossetia, Georgia back in 2008, and all Bush did was impotently wax indignant over it. Everyone and their mom knew he wasn't going to do crap about it, just like Obama today.
Fact is, most Americans don't care, and certainly don't want a war with a country as powerful as Russia over a nation they couldn't pick out correctly on a world map. People are sick on intervention, just look at the mass outcry when it seemed as though Obama might bomb Syria.