U.S. airstrikes target Syrian regime vehicles near al-Tanf base

May 18 (UPI) -- The U.S. Air Force targeted a convoy of vehicles belonging to Syrian President Bashar al-Assad after they came within 18 miles of a secure U.S. base at al-Tanf, a training center for Syrian rebels.

The attack is the first since a series of bombings in April undertaken by the United States specifically targeting Assad's forces for their use of chemical weapons against civilians.

CBS News reported the convoy of 27 government vehicles approached al-Tanf in southwestern Syria, where U.S. special forces are training Syrian rebels in the fight against Assad. Warplanes buzzed the convoy in an effort to get them to turn around. When they did not, the U.S. fighter jets targeted some of the Syrian vehicles and opened fire.

It was not clear if there were any casualties.

In a second incident near al-Tanf, U.S. fighter jets intercepted a Syrian SU-22 fighter-bomber that had entered air space near the base. There was no exchange of fire and the Syrian bomber turned around.

Al-Tanf was attacked previously by the Islamic State.

IS fighters also launched an offensive against Assad-held territory in the western province of Hama, seeking to take control of a strategic supply route leading to the nation's largest city Aleppo. Unofficial accounts said the attack killed 50 people, including 12 civilians.