Less than a week after President Donald Trump formally ordered the U.S. military to withdraw the majority of its forces from Syria, the Pentagon carried out an unusual mission in the northeastern part of the country. A pair of F-15E Strike Eagle fighter jets delivered a precision airstrike, not to protect a joint U.S.-Turkish patrol on the border or bomb an ISIS haven back to the Stone Age, but to destroy a major U.S. ammo cache housed in a former cement factory that had been converted into a U.S. special operations base and Kurdish training camp. The stated reason: to “reduce the facility’s military usefulness.”

This unusual mission underscores the logistical nightmares wrought by a hasty U.S. military withdrawal from the country. Military sources have told reporters that the sortie, which cost roughly $23,000 per hour per aircraft, was ordered “because the cargo trucks required to safely remove the ammo are needed elsewhere to support the withdrawal.” Army Colonel Myles Caggins, a spokesman for the U.S.-led coalition in Syria and Iraq, tried to play the incident off as routine, saying that “blowing the ammo was part of the plan,” but Brett McGurk, a former U.S. envoy to the multinational alliance, tweeted that the mission constituted an “emergency ‘break glass’ evacuation procedure reserved for an extreme worst-case scenario.”

McGurk isn’t wrong. “Trying to destroy munitions from the sky like this does not work as well as air planners think,” John Ismay, a New York Times reporter and former Navy explosive ordnance disposal officer, tweeted. “Some of the weapons you hit will detonate sympathetically, sure. For the rest, you’ve blown open secure storage and made it available to anyone with a pickup truck.”

It’s that latter prospect that should be concerning. In 2017, Trump shuttered a CIA program to arm and equip Syrian rebels, and the weapons and ammo left behind may have helped spur what one researcher on the ground has called an “industrial revolution in terrorism”—and in the midst of Trump’s hasty about-face in northern Syria, even more powerful U.S. munitions stand poised to fall into enemy hands.

That U.S. arms end up in enemy hands is no surprise. A 2017 report from arms control group Conflict Armament Research found that ISIS had captured “significant quantities” of NATO weaponry after looting Iraqi weapons depots in 2014. The lion’s share of “found” ISIS weapons were Warsaw Pact-era firearms and ammo caches that likely originated in Russia and China, but many more foreign-pattern arms “were purchased by the United States and Saudi Arabia” from E.U. nations to equip Syrian opposition forces “without authorisation”—that is, without getting permission from the supplying government to redistribute the weapons. “Supplies of materiel into the Syrian conflict from foreign parties—notably the United States and Saudi Arabia—have indirectly allowed IS to obtain substantial quantities of anti-armor ammunition,” according to the CAR report. “These systems continue to pose a significant threat to the coalition of troops arrayed against IS forces.”