Bad news in America’s five-year-old proxy war against al-Qaida-allied Somali insurgents. Half of the U.S.-supplied weaponry that enables cash-strapped Ugandan and Burundian troops to fight Somalia’s al-Shabab terror group is winding up in al-Shabab’s hands.

The kicker: it’s the cash-strapped Ugandans who are selling the weapons to the insurgents.

This revelation, buried in U.N. reports and highlighted by controversial war correspondent Robert Young Pelton at his new Somalia Report website, raises some unsettling questions about Washington’s plans to out-source more wars in the future.

Shabab is...