I trust President Obama (with no doubts) to handle this crisis in Ukraine as best as it can be handled. I trust and admire him as much as the great FDR. That said it is a horrible situation that he has been handed and I fear the dye was cast when the W administration occupied Iraq...I admit to being a 'worry-wart', but here is what worries me now.
Briefly, as the Iraq War unfolded, I was puzzled as to why Russia and China didn't condemn it far more strongly than they did. Why did they never unite to demand UN sanctions against the US for such a clearly criminal act of naked aggression. But then it came to me. Russia and China liked the idea of the US invading and occupying Iraq for two reasons. Firstly, they knew it would cost us militarily and financially, but worst of all for the US, the Iraq war cost us the hard earned credibility and global sympathy which came our way after the 9-11 tragedy. Secondly and most importantly our unlawful invasion of Iraq gave Russia and China the 'moral blank check' they wanted for their own planned future land grabs.
After the United Nations condemned, but never took action against the US to stop the Iraq war the precedent is now set for NATO to vote only for weak and tepid sanctions (if any) against Russia, even if they take over all of the Ukraine. And the Genie is out of the Bottle now, a move by North Korea into South Korea will become far more likely and China is just waiting their turn to make a land grab of their own, perhaps into Taiwan and or some of Japan's Islands.
As I said then, the Iraq war could lead to WWIII.