The world is waiting for the Trump administration to explain the legal rationale for its assaults on alleged drug-trafficking boats. As a self-proclaimed crusader against overly restrictive rules of engagement, Defense Secretary Pete Hegseth has disclaimed any duty to justify the strikes. But if the news reports have it right, the attacks have crossed a line in international law too bright to ignore. U.S. troops are supposed to know where these lines lie, but Hegseth seems to have missed that lesson.

I learned it firsthand outside of Fallujah in 2004. My friend Dan Malcom and I attended a briefing on the rules of engagement for the battle we were about to fight. Al-Qaeda in Iraq had turned the city into a stronghold over the previous six months. The Judge Advocate General (JAG) on our staff explained that the rules of engagement would be different from the ones we’d followed up to that point in the insurgency. For weeks, the Iraqi government and 1st Marine Division had warned all civilians to evacuate Fallujah. When the assault began, any military-age male remaining in the city would be presumed hostile. They could be engaged as an enemy combatant and killed on sight.