China has lodged representation with the U.S. over the latter’s sanctions of a Chinese citizen and three Chinese companies that allegedly supported and provided equipment to Iran’s ballistic missile program. China stands by its opposition to unilateral sanctions.

“China opposes all forms of proliferation and organizes its non-proliferation work in accordance with domestic policies, laws and regulations, while strictly fulfilling its international obligations and promises. We hope that relevant concerns over non-proliferation can be resolved through dialogue and cooperation on the basis of mutual respect, equality and mutual benefit,” said a spokesperson for the Ministry of Foreign Affairs, Hua Chunying, during a press conference on May 18.

Hua stressed that China always opposes unilateral sanctions, especially when such sanctions jeopardize the interests of a third party.

Hua’s remarks were made in response to the U.S. Department of the Treasury’s sanction of a China-based network for supporting Iran’s ballistic missile program. The sanction applies to one Chinese national and three Chinese companies. According to the treasury’s official announcement, Ruan Runling is a Chinese proliferation agent who has supplied Iran's Shiraz Electronics Industries with items and technology related to missiles, including goods originating from the U.S.

This is not the first time that a Chinese company or individual has been accused of violating U.S. sanctions. In March, China’s telecom giant ZTE was forced to pay a record-breaking fine of $892 million for providing Iran with sensitive technologies.