The United States is seeking to confirm reports that Iran launched a ballistic missile last month in violation of UN sanctions and may raise the issue before the UN Security Council.
"It is extremely important that the Security Council resolutions be enforced," U.S. Ambassador to the United Nations Samantha Power said December 8.
In October, the United States, Britain, and France called for council action over a similar test by Tehran of a nuclear-capable missile that they said violated UN sanctions.
So far, no action has been taken.
Power said council members will discuss the issue next week and the United States could take unilateral steps against Iran.
Tehran says its missiles are not designed to carry nuclear weapons and therefore don't violate UN sanctions.
U.S. Senate Foreign Relations Committee Chairman Bob Corker condemned the lack of response to "repeated" Iranian violations.
"Iran violates UN Security Council resolutions because it knows neither this administration nor the UN Security Council is likely to take any action," Corker said.
France said on December 8 it would pay close attention to ensure Iran respects the ban on ballistic-missile tests.