As the United Nations Security Council met on Tuesday to discuss Iran’s Sunday test-launching of a medium-range ballistic missile, military officials confirmed that the country also secretly tested another missile in early December.

Tehran fired a Shahab-3 on Dec. 6 at Semnan, though the missile’s destination is unknown. The intermediate range ballistic missile is modeled off a North Korean design and has a range of 800 miles, according to a report. Officials said the test was likely in breach of UN Resolution 2231, which was signed after the Iran nuclear deal. It called for a stop to “any activity” related to ballistic missiles’ carrying nuclear weapons.