Captain, you couldn't be more wrong.
First, the only valid reason for sending US troops into combat is to protect vital US interests. We have none in Ukraine. We have none in syria either. We had none in Libya but we meddled there anyway. How did that work out? We destabilized Iraq, then showed how naive we were by trying to engage in Good Humor man nation-building. How did that work out? Afghanistan? Big success there or nightmare?
Second, we are the ones who need to learn a lesson, not putin. He was minding his own business, unlike us, until we fomented a crisis and overthrew an elected government in Ukraine. The new government is anti-russian. Lots of russians live in Ukraine and didn't like it.
Third, the idea that Obama should put troops into a dangerous situation without congressional approval is unacceptable to me. You and McCain seem to be pining for us to get into a shooting situation with Russia. You want to start brandishing nukes over a place most Amercians couldn't find on the map. McCain was all frothing at the mouth for us to go into Ssyria too. Then it turns out we would be on the side of the people he wants us to go into Iraq to fight. Get it straight, ok?