Matt Continetti puts it well over at the Free Beacon:
Which brings us to the final straw man Trump lit on fire. When President Obama punted on Syria in 2013, he claimed there was no international support for limited intervention. True, David Cameron lost a vote in Parliament on the matter. But the actual powers Obama didn’t want to offend were Iran and Russia. He worried they would scuttle the Iran nuclear deal as payback. The loss of American credibility, the confidence of allies, and Syrian civilians were all factored into the cost of an Iranian promise not to test a bomb for 10 years.
Well, the rapprochement with Iran, if it ever existed, is over. In recent weeks President Trump has met with the leaders of our traditional Sunni allies: Saudi Arabia, Egypt, and Jordan. He has signed off on aid to Saudi in its war against Iranian proxies in Yemen. He has approved weapons to Bahrain, which is worried about Iranian influence over its Shiite population. America is heavily involved in Iraq and Syria. And now, by striking Assad, President Trump has targeted Iran’s most prominent servant.