It has been a very, very long time since John McCain has lived up to his "Maverick" reputation -- so much so that you'd be entirely forgiven for thinking the Arizonan senator was just another hack Republican looking after American corporate interests for a living.
However, the election of Donald Trump and the real possibility of a complete break up of the international system that has (largely) kept the peace for 70 years seems to have rattled him. Here he was on the Trump administration "partial responsibility" for Syria's horrific chemical attack on its own citizens (via CBS News):
Sen. John McCain, R-Arizona, said comments made by people in President Donald Trump’s administration are “partially to blame” for encouraging Syrian President Bashar al-Assad’s apparent use of chemical weapons on his people last week.
McCain responded to remarks that Secretary of State Rex Tillerson made at the end of March, before the attack, including comments that the Syrian people would determine Assad’s fate, and that removing him from power isn’t a top priority.
“I think it probably was partially to blame,” McCain said. “And Secretary Tillerson basically saying the same thing after kind of contradicting himself and then saying the same thing argues vigorously for a plan and a strategy. As I said again, taking this action I support and was important.”
I don't agree with McCain that bombing Syria was the right thing to do (I'm not sure there is a right thing to do), but Trump's refusal to take a stance on Assad and his brutal regime clearly gave the repressive dictator the courage to commit more atrocities in front of the international community. Trump has long held the position that Syria is none of America's business and is a stabilizing force for the region. While Obama was explicit in his condemnation of Assad's horrendous government and attempted to work with the international community to prevent him from brutalizing his own people, Trump has basically signaled that he doesn't care what they do as long as they are fighting ISIS. It may be unfair to lay all of the blame at Trump's feet, but as McCain says, there is at the very least some partial responsibility.
The real story here though is McCain's increasingly hostile position towards the Trump administration -- a very encouraging sign that some Republicans have the bottle and willingness to publicly rebuke them. While the Democrats can do much to damage the Trump administration, the biggest wins will come from factional fighting within the Republican Party. While the Alt Right movement is falling apart in real time and Trump looks for help from the establishment, John McCain is doing his part to ensure he never gets it. McCain may not be the Maverick he once was, but even he understands that this charade cannot go on and is finally doing something about it.