DAKAR, Senegal (AP) — The United States will begin plans to withdraw troops from Niger, U.S. officials said Saturday, in what experts say is a blow to Washington and its allies in the region in terms of staging security operations in the Sahel. The planned departure comes as U.S. officials said they were trying to find a new military agreement.

The prime minister of Niger, appointed by the ruling military junta, Ali Lamine Zeine, and U.S. deputy secretary of state Kurt Campbell, agreed on Friday that the two nations would begin to plan the withdrawal of American troops, the U.S. State Department told The Associated Press in an email Saturday.

U.S. officials gave no timeline about their withdrawal. An American delegation to coordinate the details of the withdrawal process will be dispatched soon.

Niger plays a central role in the U.S. military’s operations in Africa’s Sahel region, an area on the edge of the Sahara Desert. Washington is concerned about the spread of jihadi violence, where local groups have pledged allegiance to al-Qaida and the Islamic State groups. Niger is home to a major U.S. air base, in the city of Agadez, about 920 kilometers (550 miles) from the capital, Niamey, using it for manned and unmanned surveillance flights and other operations. The U.S. has also invested hundreds of millions of dollars in training Niger’s military since it began operations there in 2013.