On the same day the United Nations Security Council held an emergency meeting to discuss Iran's recent test launch of a medium-range ballistic missile, Fox News has learned of another secret missile launch, this one conducted in early December, two U.S. military officials tell Fox News.

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On December 6, nearly a month after the presidential election, Tehran fired a Shahab-3, an intermediate-range ballistic missile based on a North Korean design, capable of flying 800 miles.

Iran previously conducted two Shahab-3 missile tests last March, coinciding with a visit by Vice President Biden to Israel.

The December launch appeared to mark another breach of U.N. Resolution 2231, which forbids the Islamic Republic from conducting such tests.

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The Shahab-3 was launched as part of a military exercise, according to one official. It is not immediately clear where the missile traveled, but the launch was deemed successful.

News of another Iranian ballistic missile test came one day after Fox News first reported a new test of a medium-range ballistic missile Sunday from the Semnan launch site 140 miles east of Tehran, the first confirmed missile test after President Donald Trump assumed office.

The December test launch also occurred at Semnan, according to officials.

U.N. resolution 2231 bars Iran from conducting ballistic missile tests for eight years and went into effect on July 20, 2015, days after the U.S. and other parties agreed to the landmark nuclear deal in Vienna.

Iran is "called upon not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons, including launches using such ballistic missile technology," according to the text of the resolution meant to coincide with the nuclear agreement.

Iran has conducted at least six ballistic missile tests since the nuclear agreement and the U.N. resolution went into effect in 2015.