A mission organization said on Friday that a pilot who was kidnapped while working for the group in the West African country of Niger last year was in “good health” after his release.

The missionary pilot, Kevin Rideout, was seized from his home in Niamey, the capital of Niger, in October. A U.S. official said on Friday that Mr. Rideout had arrived at Ramstein Air Base in Germany and was undergoing medical evaluation. Like others in this article, the official spoke on condition of anonymity to discuss operational matters.

Mr. Rideout’s organization, called Serving in Mission, said in a statement that he would soon be reunited with his loved ones.

“We are grateful to confirm that our good friend and brother in Christ, Kevin Rideout, has been released,” the statement read. The mission noted that he was in “good health in the care of U.S. officials” and would soon be reunited with his wife, Krista; their four children; and his extended family.

“Krista and the rest of Kevin’s family are profoundly grateful for the prayers offered on their behalf by people around the world throughout his captivity,” the statement added.

Another U.S. official said on Thursday that Mr. Rideout’s release, which was earlier reported by The New York Times, was not the result of a military rescue operation but “by other means,” offering no further details.

The official linked Mr. Rideout’s release to U.S. military pressure on the Islamic State in Nigeria, Niger’s southern neighbor, in recent months. In May, President Trump said that American and Nigerian forces had killed Abu Bilal al-Minuki, a high-ranking Islamic State leader in Lake Chad, a region at the intersection of four countries, including Nigeria and Niger.

The official said that raid had helped influence the kidnappers’ decision to release Mr. Rideout.

How and where he was released were not yet clear, U.S. officials said earlier, and it was also unclear which group held him at the end of his captivity. Mr. Rideout’s release had been a major priority for the White House and for the military’s Africa Command.

In May, the French journalist and researcher Wassim Nasr, who has been monitoring jihadist groups in the area for several years, said that Mr. Rideout was being held in Ménaka, a region in Mali just over the border with Niger. That area is mostly controlled by a local branch of the Islamic State.

For years, Mali and Niger have been battling insurgents affiliated with Al Qaeda and the Islamic State. In April, Al Qaeda-linked militants launched coordinated attacks across Mali, seizing a major city and killing the country’s defense minister.