Story highlights 11 militants were killed in the December battle, Pentagon assesses

Four US soldiers were killed in Niger in October

(CNN) The US military revealed for the first time Wednesday that US troops were involved in a firefight in Niger in December, just months after a Green Beret-led team was ambushed by ISIS militants in October, an attack that left four US soldiers dead.

In a statement provided to CNN by Pentagon spokeswoman Maj. Sheryll Klinkel, the US military said that "during a mission in the Lake Chad Basin region the morning of Dec. 6, a combined force of Nigerien and US military members came under fire from a formation of violent extremists."

The military stressed that US troops were not seeking combat and that the joint US-Nigerien mission was aimed at setting "the conditions for future partner-led operations against violent extremist organizations in the region," adding that "no aspect of this mission focused on pursuing enemy militants."

"With that said, our forces do operate in unstable areas and are occasionally exposed to danger from enemy forces. When such a situation occurs, our personnel are authorized to respond to threats and violence appropriately," the statement added.

The statement said the military assessed that the attackers were part of the terror group ISIS-West Africa, a different group from the ISIS affiliate believed to be responsible for the October ambush that happened in a different part of the large African country.

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