The new round of sanctions, announced by the department in a statement, includes an arms dealer in Belarus and two Iranian airlines. The sanctions will make it easier to track weapons and prevent them from reaching Assad's army, which has been engaged in an 18-month conflict with opposition forces trying to topple him from power.
"Today's actions seek to disrupt the flow of weapons and communications equipment to the Syrian regime and help prevent their use against the Syrian people," the department said in a statement.
Belarus state-owned weapons manufacturer Belvneshpromservice and Syria's Army Supply Bureau were hit with the sanctions. The former Soviet bloc state remains closely allied with Russia, which supports the Assad regime. The company is accused of providing aerial bombs the Assad regime has used to target civilians as recently as July, the Treasury Department said.
The department also added Mahan Air and Yas Air to its sanction list in addition to Iran Air, which had been designated earlier.
The department also named the director of Syria's Scientific Studies Research Center, Amr Armanazi.