The United States accused Iran on Thursday of defying a UN resolution with one ballistic missile test and two satellite launches since December and urged the Security Council to impose new sanctions on Tehran. In a letter to the 15-member Council, acting US Ambassador to the United Nations Jonathan Cohen said Iran tested a medium-range ballistic missile on Dec. 1, 2018, and attempted to place satellites in orbit on Jan. 15 and Feb. 5. "Iran has carried out these three launches in defiance of the expressed will of the UN Security Council, and such provocations continue to destabilize the entire Middle East region," Cohen wrote. Security Council Resolution 2231 -- adopted just after the 2015 nuclear deal - "called upon" Iran to refrain for up to eight years from work on ballistic missiles designed to deliver nuclear weapons following an agreement with six world powers. Some states argue that the language does not make it obligatory. Cohens letter called upon the Council to "join us in imposing real consequences on Iran for its flagrant defiance of the Councils demands and bring back tougher international restrictions to deter Irans missile program." Asked for a response to the US letter, spokesman Alireza Miryousefi for the Iranian mission to the US said Tehran does not have any ballistic missiles designed to carry nuclear weapons "therefore none of the ballistic missile launches of Iran are covered by that resolution." There was no immediate request from the United States for a Council meeting to discuss Iran and no further steps were announced in the letter. At a Security Council meeting in December, US Secretary of State Mike Pompeo urged the body to toughen that measure to reflect language in a 2010 resolution that left no room for interpretation by banning Iran from "activity related to ballistic missiles capable of delivering nuclear weapons, including launches using ballistic missile technology."