The United States, Britain, France, and Germany have notified the United Nation's Iran sanctions committee of Tehran's recent ballistic missile test and demanded an investigation and "appropriate action" in response to the "serious violation."
A letter was sent to the committee late on October 21 by the United States on behalf of the four countries.
It said the launch was in breach of Security Council resolutions and the ballistic missile was "inherently capable of delivering a nuclear weapon."
"We trust that this information will assist the committee in its responsibility to examine and take appropriate action in response to violations of UN Security Council resolutions," the Western powers said.
The letter marked a first step toward possible sanctions, although such a decision would require agreement from China and Russia, which have taken a softer line toward Tehran.
Iran has disputed the assessment that the missile tested was capable of delivering a nuclear warhead.