"That's a pretty little missile cruiser you've got there, It would be a real shame if anything happened to it."
I think Trump will call the Vladman's bluff. Why not, he can't lose.
If the Russians back down, or lose a skirmish against US forces in Syria, Trump wins big time.
If The Russians have a military victory, Trump can always blame Obama for putting him in an untenable situation with no way out.
And if a general war is precipitated, no one is going to be worried much about global warming, or the S China sea, or Iran and who's responsible. It simply won't matter any more.