The U.S. on Tuesday imposed sanctions on seven people and four companies in China, Russia and Turkey who officials allege are connected with the development of Iran’s drone program.

The U.S. accuses Iran of supplying Russia with drones used to bomb Ukrainian civilians as the Kremlin continues its invasion of Ukraine.

The latest development comes after Iran’s President Ebrahim Raisi denied his country had sent drones to Russia for use in the war in Ukraine.

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“We are against the war in Ukraine,” President Raisi said Monday as he met with media executives on the sidelines of the world’s premier global conference, the high-level leaders’ meeting at the U.N. General Assembly.

The parties sanctioned Tuesday by Treasury’s Office of Foreign Assets Control include: An Iranian drone company previously sanctioned in 2008, now doing business as Shahin Co., its managing executives, a group of Russian parts manufacturers and two Turkish money exchangers, Mehmet Tokdemir and Alaaddin Aykut.

Treasury said the action builds on a set of sanctions it issued last March, when Treasury sanctioned 39 firms linked to an alleged shadow banking system that helped to obfuscate financial activity between sanctioned Iranian firms and their foreign buyers, namely for petrochemicals produced in Iran.

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Brian E. Nelson, Treasury’s undersecretary for terrorism and financial intelligence, said Iran’s “continued, deliberate proliferation” of its drone program enables Russia “and other destabilizing actors to undermine global stability.”

“The United States will continue to take action” against Iran’s drone program, he said.

Matthew Miller, a spokesman for the State Department, said the U.S. “will continue to use every tool at our disposal to disrupt these efforts and will work with Allies and partners to hold Iran accountable for its actions.”

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Among other things, the sanctions deny the people and firms access to any property or financial assets held in the U.S. and prevent U.S. companies and citizens from doing business with them.

Tensions between the U.S. and Iran remain high, despite the release of five American detainees from Iran this week in exchange for the release of nearly $6 billion in frozen Iranian assets.