A display featuring missiles and a portrait of Iranian Ayatollah Ali Khamenei is seen at Baharestan Square in Tehran, Sept. 27, 2017. Photo: Nazanin Tabatabaee Yazdi / TIMA via Reuters.

China rejected on Thursday a planned push by the United States to extend a United Nations arms embargo on Iran and, if that fails, Washington’s assertion that it could trigger a return of all sanctions on Tehran at the UN Security Council.

US special envoy for Iran, Brian Hook, publicly confirmed the US strategy on Wednesday, two weeks after a US official, speaking on condition anonymity, said the United States had told Britain, France and Germany of its plan.

China’s mission to the United Nations in New York said that by quitting the Iran nuclear deal in 2018, Washington had “failed to meet its obligations” under a 2015 Security Council resolution that enshrined the agreement.

Tehran was given sanctions relief under the deal with the United States, Russia, China, Germany, Britain and France that prevents Iran from developing nuclear weapons. The deal — known as the JCPOA — allowed for a so-called snapback of sanctions, including the arms embargo, if Iran violated the deal.

China’s UN mission posted on Twitter that the United States “has no right to extend an arms embargo on Iran, let alone to trigger snapback. Maintaining JCPOA is the only right way moving forward.”

Under the nuclear deal, a UN arms embargo is due to expire in October.

Hook said that the United States has drafted a Security Council resolution to extend the arms embargo on Iran. A resolution needs nine yes votes and no vetoes by Russia, China, the United States, France or Britain to be adopted.

Russia has already signaled its opposition to extending the arms embargo on Iran and the US claim that it can trigger the return of all sanctions on Tehran.

US President Donald Trump branded the accord from Barack Obama’s presidency as “the worst deal ever.” Washington argues it can trigger a return of UN sanctions because the Security Council resolution still names the US as a participant.

Diplomats say the United States would likely face a tough, messy battle if it tries to spark a return of sanctions, though it was not immediately clear how or if a Security Council member could stop such a move.

Iran has breached several central limits of the deal, including on its stock of enriched uranium, in response to the US withdrawal and Washington’s reimposition of sanctions that have slashed Iran’s oil exports. Britain, France and Germany are trying to save the deal, but have made little progress.