Mr. Assad all but created Islamic State through his slaughter of nearly 200,000 Syrians, and he has knowingly allowed the group to grow and operate with impunity inside the country when it suits his purposes. Until we confront this reality, we can continue to degrade Islamic State in Syria, but Mr. Assad’s barbarism will continue to empower it.

This points to another contradiction: How can we arm and train 5,000 Syrians and expect them to succeed against Islamic State without protecting them (and their families) from Assad’s airstrikes and barrel bombs? Or expect moderate groups in Syria fighting Islamic State to take advantage of U.S. airstrikes if we do not coordinate or communicate our operations with them? This is reportedly not happening. Instead, Mr. Assad is exploiting U.S. airstrikes to kill the very people we want as our partners. This is not just a recipe for failure; it is immoral.

Our efforts to build up a viable Free Syrian Army to liberate Syria from the evils of Islamic State and Mr. Assad will surely fail if the Syrian ruler is not dealt with. To expect Mr. Assad to sit on the sidelines as the Free Syrian Army gains capacity would be a colossal mistake and doom efforts to stop Syria from sinking further into the abyss.