Because I'm sure the Republican Party would have been totally OK with Obama attacking Assad without seeking Congressional authorization first - which he was denied, of course, with many Republicans voting against him.

Meanwhile, Dear Leader Trump bombs Syria without seeking any authorization from Congress whatsoever, and all of a sudden he's a brave American hero (well most Republicans already thought that, but still).

Clearly Republicans wouldn't ever sabotage America's international reputation and let millions of people be killed or forcibly displaced by murderous Middle Eastern regimes or Islamic jihadists just to score political points against the President of the United States (D - Kenya). After all, they're the "America First" party. Right?