The US imposed sanctions on a man accused of overseeing the Wagner Group’s operations in Mali, as allied nations look to crack down on Russian efforts to run guns through West Africa in support of the Ukraine invasion.

The Treasury Department sanctioned Ivan Maslov, identified as the head of Wagner’s paramilitary units and its most senior official in Mali, according to a statement. The sanctions “disrupt a key operative supporting the group’s global activities,” Undersecretary for Terrorism and Financial Intelligence Brian Nelson said.

Earlier this week, the US said it suspects Wagner is trying to ship weapons to fighters in Ukraine through Mali using false paperwork and other ways of obfuscating where the guns are headed.

US Says Russia’s Wagner Group Moving Weapons to Ukraine via Mali

The US has repeatedly imposed sanctions on Wagner and its leadership structure, including the man who created it, Yevgeny Prigozhin. Those efforts have so far made little dent in the group’s operations, including its push to deepen a toehold in several African nations.