A second firefight in Niger reported

WASHINGTON — Green Berets working with government forces in Niger killed 11 Islamic State militants in a firefight in December, the U.S. military acknowledged for the first time Wednesday.

The battle occurred two months after four U.S. soldiers died in an ambush in another part of Niger — and after senior commanders had imposed stricter limits on military missions in the West African country.

No U.S. or Nigerien forces were harmed in the December gunbattle. But the combat — along with at least 10 other previously unreported attacks on U.S. troops in West Africa between 2015 and 2017 — indicates that the deadly Oct. 4 ambush was not an isolated episode in a nation where the United States is building a drone base.

After the ambush, senior officers at U.S. Africa Command imposed additional measures to enhance the safety of troops on missions that were designed to train and advise local forces in Niger.

But on the morning of Dec. 6, a combined force of Nigerien and U.S. troops “came under fire from a formation of violent extremists,” Samantha Reho, a spokesman for Africa Command, said in a statement to The New York Times on Wednesday.

She said the gunbattle killed 11 militants who were believed to be affiliated with the Islamic State in West Africa. No U.S. or Nigerien forces were killed or wounded, she said, giving no explanation for the Pentagon’s failure to disclose the episode at the time.

The head of Africa Command, Gen. Thomas Waldhauser, did not mention that gunbattle in testimony to Congress this month and only broadly outlined threats in the region. A senior House Republican aide said Wednesday that lawmakers had been notified about the attack soon after it happened.