A UK-based organization monitoring Syria says regime forces of Bashar Al-Assad along with Iranian militias have conducted joint exercises near the border with Iraq.

The Syrian Observatory for Human Rights (SOHR) announced Wednesday the joint night maneuvers were staged at the outskirts of Homs Governorate where Al-Tanf base is located.

Al-Tanf is a US military base within territory controlled by the Syrian opposition. It is located 24 km west of the al-Tanf border crossing along the Iraq and Jordan-Syria border.

The Syrian Observatory says heavy weapons were used to raise the fighting readiness of their forces, coinciding with explosions heard in Al-Omar oil field, which is the largest “International Coalition” base in Syria.

Earlier this month, SOHR said it was informed that “Russian officers, Iran’s Revolutionary Guard officers as well as Afghan Fatemiyoun militia are present east of Palmyra in eastern Homs countryside near Al-Tanf base.

Fatemiyoun Brigade is an Afghan Shia militia formed and supported by Iran since 2014 to fight in Syria on the side of the Bashar al Assad’s forces.

“These drills were designed to train Iranian-backed militiamen on the use of short and medium-range Iranian-made missiles on inanimate targets in the Syrian desert and Palmyra military airbase,” added SOHR.

The region has been the scene of clashes between Iranian-backed forces and US troops.

Iran has long backed the Syrian president, Bashar al-Assad’s, government in Syria’s grinding civil war. Iran says it has no troops in Syria but the IRGC military “advisers”.