It is important also to consider that the statement that Gen. Mattis gave is not that he says he disagrees with the Trump decision to launch the Tomahawk strike. He is only saying there is no evidence in his possession that confirms the the Syrian government was behind these attacks.
We’ve seen it over and over again. In Libya, western interventionism was justified under the pretense of defending human rights when the goal was actually regime change. In Ukraine, empire loyalists played cheerleader for the protests in Kiev when the goal was actually regime change. And who could ever forget the poor oppressed people of Iraq who will surely greet the invaders as liberators?