Russia has sharply criticized a recent decision by the United States to deploy two units of HIMARS multiple rocket launchers to a base in eastern Syria.
In a statement on June 15, the Russian Defense Ministry said that "deploying any type of foreign weapons on Syrian territory...must be approved by the government of that sovereign country."
The Russian statement suggested that the rocket launchers would be used for strikes against Syrian government forces.
The Pentagon announced the deployment of the truck-mounted high-mobility artillery rocket system (HIMARS) on June 14, saying they were intended to defend the Al-Tanaf base where the U.S.-led international coalition is training locals to fight against Islamic State (IS) forces.
The system can launch six guided rockets at targets within a 70-kilometer range or a single missile at a target as far away as 300 kilometers. The Pentagon said it was not the first time HIMARS systems had been deployed in Syria and Iraq to support the fight against IS.
On June 6, the U.S.-led coalition said it had eliminated a unit of Iranian-backed forces fighting on behalf of Syrian President Bashar al-Assad as it neared the Al-Tanaf base. Russia denounced that attack as an "act of aggression."
Russia has been conducting air strikes and providing other military support to Assad in his fight against rebel forces since September 2015.