United Nations, United States, March 7, 2019 (AFP) -

The United States on Thursday accused Iran of carrying out three missile-related launches in defiance of U.N. resolutions and urged the Security Council to "bring back tougher international restrictions" against Tehran.

In a letter to the council seen by AFP, U.S. acting Ambassador Jonathan Cohen warned Iran's activities were destabilizing the entire Middle East and risk triggering an arms race.

Cohen singled out a December 1 launch of a medium-range ballistic missile and the January 15 and February 5 attempts by Iran to place satellites into orbit using space launch vehicles.

"Iran has carried out these three launches in defiance of the expressed will of the U.N. Security Council, and such provocations continue to destabilize the entire Middle East region," said the letter seen by AFP.

The United States called on the council to "join us in imposing real consequences on Iran for its flagrant defiance of the council's demands and bring back tougher international restrictions to deter Iran's missile program."

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.

U.N. Security Council Resolution 2231 -- adopted just after the 2015 nuclear deal -- calls on Iran "not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons."

Tehran insists that its missile development program is defensive and in compliance with the resolution, but the United States has repeatedly challenged that stance.

In the letter, the acting ambassador said the December 1 launch was "designed to be capable of delivering nuclear weapons" and that the space launch vehicles use technologies that are "virtually identical and interchangeable" with those used by ballistic missiles.

"Iran's January 15 and February 5 satellite launches constitute activities using technologies related to ballistic missiles designed to be capable of delivering nuclear weapons," wrote Cohen.

"The prospect of rapid escalation in the region is real, and increasingly likely, if we fail to restore deterrence," he added.

Iran reined in most of its nuclear program under the landmark nuclear deal with major powers but has kept up development of its ballistic missile technology.

President Donald Trump pulled the US out of the nuclear accord in May last year and reimposed sanctions on Iran, citing concerns about missile development among its reasons.

At a council meeting in December, US Secretary of State Mike Pompeo called for tighter restrictions on Iran to curb its missile program but Russia flatly asserted that there was no proof that Iran's missiles can carry a nuclear payload.