There were no U.S. military injuries or deaths resulting from a coordinated attack Wednesday on a small remote U.S. military base at al Tanf, Syria, according to two U.S. officials.

The attack “at a minimum” involved drones and “indirect fire,” the military term for mortar or rocket fire, according to a U.S. official.

Iraqi security sources said the attack involved five booby-trapped drones and was carried out from inside Syria.

There is no indication yet as to who may have been responsible for the attack, but similar drone attacks against U.S. forces in Iraq have been a tactic used by Iranian-backed militias, most notably Kataib Hezbollah.

Drone attacks attributed to those militias have at times resulted in American retaliatory airstrikes in Iraq and Syria targeting their facilities.

The remote base at al Tanf is located along a key highway in southern Syria on the border with Jordan and is surrounded by a 35-mile buffer zone to prevent potential conflicts with Russian and Syrian government troops located nearby.

The small outpost is the only American military base in Syria not located in Syrian Kurdish-held areas in eastern Syria where most of the 1,000 American troops in Syria are based.

U.S. troops remain in Syria as part of an ongoing effort to prevent ISIS from regaining territory inside that country.

ABC News’ Bader Katy contributed to this report.