The Obama administration on Sept. 19 moved to punish companies from Belarus and Iran for allegedly providing Syria with weapons and communications gear used to battle rebels in the country’s 18-month-old civil war.

Treasury Department officials also announced sanctions against a Syrian army supply group and a Syrian scientist suspected of overseeing the production of some of the country’s chemical weapons.

The sanctions and other measures are the latest in a series of steps intended to squeeze Syria’s economy and discourage foreign governments from aiding Syria’s armed forces and its beleaguered president, Bashar Assad.

The actions “seek to disrupt the flow of weapons and communications equipment to the Syrian regime and help prevent their use against the Syrian people,” said David S. Cohen, Treasury’s undersecretary for terrorism and financial intelligence.