In the annals of military history there are many notable blunders, but Wednesday’s ill-fated attack by pro-regime forces against a heavily fortified headquarters for U.S.-backed anti-Islamic State fighters in eastern Syria ranks up there in the ranks of really bad ideas.

A battalion of about 300 troops, loyal to Bashar Assad, supported by artillery, tanks, multiple-launch rocket systems and mortars crossed a well-established deconfliction line and began shelling an area where U.S. special operations forces are advising units of the Syrian Democratic Forces in their final push to defeat ISIS in the Middle Euphrates River Valley.