NIAMEY (Reuters) - A part of southwestern Niger where four U.S. Green Berets were killed during a mission the U.S. military had considered low-risk has seen at least 46 attacks by armed groups since early last year, a U.N. agency said on Friday.

The deaths of the four U.S. soldiers and ensuing confusion over what happened during the Oct. 4 ambush have thrown a spotlight on the U.S. counter-terrorism mission in the West African nation, where about 800 U.S. troops are deployed.

Four Nigerien soldiers were also killed.

U.S. forces do not have a direct combat role in Niger and instead provide assistance to its army, including intelligence, surveillance and reconnaissance support.

Several Islamist militant groups are known to operate in the area near the border with Mali where the ambush occurred, however, and U.S. officials later said a local Islamic State affiliate was suspected of carrying it out.

Following the attack near the village of Tongotongo, the U.S. military’s Africa Command said the soldiers’ mission to meet with local leaders was considered low-risk so there was no armed air cover.

“According to non-exhaustive information gathered in the (Tahoua and Tillabery) regions, 46 attacks perpetrated by armed groups have been recorded,” a note from the U.N. humanitarian coordination agency said on Friday.

Seven districts in the Tahoua and Tillabery have been under a state of emergency since March, and the government renewed the measure for an additional three months on Sept. 18. Niger’s army launched a military operation to reestablish security in Tillabery in June.

The deadly incident has become a political football in Washington amid criticism of U.S. President Donald Trump’s handling of condolence messages to the families of the dead soldiers.

Senator John McCain, chairman of the Senate Armed Services Committee, said on Thursday he may consider issuing a subpoena because he said the White House has not been forthcoming with details of the ambush.

From initial accounts, the 40-member patrol, which included a dozen U.S. troops, came under attack by militants riding in a dozen vehicles and on about 20 motorcycles.

Under heavy fire, U.S. troops called in French fighter jets for air support, but the firefight was at such close quarters that the planes could not engage and were instead left circling overhead.

French aircraft evacuated the wounded, but the body of one of the dead soldiers was recovered by Nigerien soldiers only after two days.

U.S. Defense Secretary Jim Mattis told reporters on Thursday that the incident was under investigation and defended the military’s response, even as he acknowledged that it did not yet have all the accurate information on the incident.