[ninty]

IMO, Iran is the flashpoint.

Both Russia and China have a lot of monry invested in Iran. I doubt they'll just stand by if the US decides to do something there.

I believe China gets 15 or 17% of its oil imports from Iran. If the US takes that oil away, China isn't going to be happy. Especially since their looking for every drop they can get.

Putin is also looking to change the constitution so he can serve a third term. The end of Democracy in Russia, if there ever was any at all?

Edit:

I suppose Taiwan could be a flashpoint as well, but I really don't see the US sending troops to counter China in that situation.