When U.S. Defense Secretary Pete Hegseth announced Friday morning that the federal government had reached an agreement with Qatar to build a facility at an Air Force base in Idaho, social media posts began popping up online from people across the political spectrum expressing outrage at the concept of a foreign military base on American soil.But the facility being built at the Mountain Home Air Force Base in Idaho isn’t a separate base at all — it is a group of buildings that will be built to handle training and maintenance for Qatari troops — and the agreement with Qatar has been in the works for years.“What we expect is it to be squadron operations and hangars for the F-15QA, because that’s the Qatari version of the jet that they bought through foreign military sales,” Air Force spokesperson Ann Stefanek said. “It is definitely still a U.S. Air Force base.”In fact, on-site training agreements with allies are common in the U.S. The Republic of Singapore 428th Fighter Squadron Buccaneers have been hosted at the base since 2008. German forces trained at the Holloman Air Force Base in New Mexico for decades. New facilities to train international F-35 fighter pilots were completed at Ebbing Air Force Base in Arkansas last year.Here are some things to know about international training agreements and the Mountain Home Air Force base.Where is the Mountain Home Air Force Base?The base is roughly 50 miles (80.47 kilometers) southeast of Boise, which is the state’s capital and primary population hub. It sits on a high desert tundra plateau tucked between two mountain ranges. The spot is ideal for fighter pilot training because there is a lot of space around the base to practice maneuvers.The base is just outside of the town of Mountain Home, which is home to about 17,000 people. The new facilities will be built by local construction crews, and local workers will likely be employed at the base to support the training operations, Stefanek said. The construction and other associated expenses will be funded by Qatar.Security at the base will continue to be handled by U.S. Air Force personnel, she said, and anyone going to the base will still have to show the proper credentials in order to enter.What is the mission of the base?The base — nicknamed the “gunfighter” base — houses the 366th Fighter Wing and more than 50 F-15E Strike Eagle aircraft. It aims to “provide mission-ready Gunfighters to conduct military operations anytime, anywhere,” according to its website.Three fighter squadrons are located there: The 389th Fighter Squadron Thunderbolts, the 391st Fighter Squadron Tigers, and the Singaporean 428th Fighter Squadron Buccaneers. An Air Control squadron and Air National Guard squadron are also housed at the base.All told, the fighter wing includes about 5,100 military and civilian members, as well as 3,500 family members, according to the website.When was the Qatar agreement conceived?Qatar decided to buy the F-15QA aircraft from a U.S. government program called Foreign Military Sales in 2017, and discussions to train Qatari troops in the use of the jets began shortly thereafter, Stefanek said.Work got started on an environmental assessment to determine the possible impact on the area surrounding the Mountain Home Air Force Base began around 2020, and the assessment was completed in 2022.Why are some upset by the announcement?Right-wing influencer Laura Loomer — a close Trump ally — called the plan “an abomination.”“No foreign country should have a military base on US soil. Especially Islamic countries,” Loomer wrote in a social media post after Hegseth’s announcement.Similar training agreements have faced criticism in the past. In 2019, a Saudi Air Force officer training at the Pensacola Naval Air Station in Florida killed three U.S. service members and wounded several others in a mass shooting. After investigating, the U.S. sent home 21 Saudi military students after investigators said they had expressed jihadist or anti-American sentiments on social media or had “contact with child pornography” online.Others suggested the training facility was prompted by Qatar’s gift to Trump of a $400 million jumbo jet to use as Air Force One, though the possibility of a training agreement predated the gift.What does the U.S. get out of the agreements to host foreign troops?The U.S. sells defense equipment and services to other countries as a foreign policy tool. A federal law called the Arms Export Control Act details when those sales can take place. But generally speaking, it is when the president determines that doing so will boost the security of the U.S. or promote peace around the world.The U.S. military often works in conjunction with other allied or friendly nations on deployment, so well-trained allies can help keep U.S. troops safe.“This partnership will provide advanced training opportunities and foster combined operational readiness for our two countries,” Stefanek said.This story was originally featured on Fortune.com