“War is hell,” Gen. William Tecumseh Sherman famously told a graduating class at the Michigan Military Academy. Yet even Sherman had some scruples and standards when it came to warfare. At least he had the conscience to recognize the evils and losses of war as “folly, madness, a crime against civilization!”

Modern military forces have rules of engagement, and most nations agree to rules of conduct in combat to constrain the most vile actions that bloodlust can foster. Violations can lead to war crime trials.

What then do we make of reports from Iraq where the Islamic State’s forces are fighting to extend their control and influence.

According to reports this week, Islamic State forces lined up dozens of unarmed Yazidi men and executed them with automatic weapon fire before abducting their women and children.

Yazidis practice an ancient religion and the Islamic State consider them to be infidels.

This kind of barbarism cannot be tolerated. The U.S. response must be to provide support and all necessary weapons to forces that are willing to take them on.