Osan Air Base is a United States Air Force (USAF) and Republic of Korea Air Force (ROKAF) base located near Songtan Station in the city of Pyeongtaek, South Korea, 64 km (40 mi) south of Seoul. Despite its name, Osan AB is not within Osan City, which is 7.5 km (4.7 mi) to the north. The base is the home of the headquarters for Seventh Air Force, Pacific Air Forces' 51st Fighter Wing, and a number of tenant units. The base is also the headquarters of the Republic of Korea Air Force (ROKAF) Operations Command. Osan Air Base is also the departure and arrival point for U.S. government-contracted "Patriot Express" flights bringing service members and their family members to South Korea from Seattle-Tacoma International Airport in the U.S. state of Washington, Misawa Air Base and Yokota Air Base in Japan.

Pyeongtaek is a city in Gyeonggi Province, South Korea. Located in the southwestern part of the province, Pyeongtaek was founded as a union of two districts in 1940, during the Goryeo dynasty. It was elevated to city status in 1986 and is home to a South Korean naval base and a large concentration of United States troops. The South Korean government plans to transform Pyeongtaek city to an international economic hub to coincide with the move of the United States Forces Korea (USFK) to Pyeongtaek. During the Korean War, it was the site of an early battle between U.S. and North Korean forces, the Battle of Pyongtaek. It is the location of Pyeongtaek University.