China is contesting U.S. sanctions against more Chinese firms for their alleged attempts to get around U.S. export restrictions on Russia, calling it an illegitimate action that puts global supply chains in peril.

Five companies with headquarters in Hong Kong and mainland China were added to the “entity list” by the U.S. Commerce Department on Wednesday, preventing them from doing business with any U.S. companies without first obtaining a special licence.

Sanctions against foreign companies that Washington believes are aiding Russia in its conflict in the Ukraine are being enforced more strictly, forcing them to choose between doing business with Moscow or the United States.

The U.S. action, according to a statement from China’s Commerce Ministry, “has no basis in international law” and was not approved by the U.N. Security Council.