DJT is becoming a hostage president.
Trump is following through on Obama’s promise to bomb Syria
He inherited and then backed up the policy of no chemical weapons use.
Having supported and backed up that policy with force once already, he can't just change his mind because the Paulite tinfoil hat brigade here wants him to do so, particularly in light of the growing Iranian threat.
The most foolish thing Trump has done recently is to have it be publicly known that he wants to withdraw from Syria.
That's what driving this. Having engaged, you don't get to call a 'timeout' and then cancel the game and walk home: the enemy always gets a vote.