There are school bus routes, baseball diamonds, and American football fields. Soldiers queue for lunch at Taco Bell, Pizza Hut, and Arby’s. A postbox stamped with the U.S. Postal Service logo stands outside a commissary stocked with American groceries. The signage is all in English, and the U.S. dollar is the currency in use. Beyond the fence, military helicopters rise above the airfield. It’s a slice of contemporary America - despite being more than 5,000 km from the U.S. mainland.
Camp Humphreys, in the South Korean city of Pyeongtaek, is the largest American military base outside the U.S.: 1,372 hectares, nearly a thousand buildings, and roughly 41,000 people, including American service members, their families, and Korean nationals. It’s the headquarters of United States Forces Korea (USFK), the clearest physical expression of the alliance that has underpinned stability on the Korean peninsula since the 1953 armistice.
Yet that alliance is now being tested. Under President Donald Trump, relations are increasingly transactional, unsettling Seoul, which has long depended on Washington as a guarantor against North Korea. “Reliability and credibility issues are worse than they were before,” says Mason Richey, a professor at Hankuk University of Foreign Studies. The alliance retains deep operational ties, he says, but the political surface has become far more fraught.
When Trump announced he would withdraw 5,000 troops from Germany after Chancellor Friedrich Merz said Washington was being “humiliated” by Iran - with threats of reductions elsewhere in Europe - Korean media asked whether South Korea would be next. The defense ministry and presidential office quickly denied any troop reduction discussions. Asked about adjustments, USFK said the current 28,500 troops was “a baseline, not a limit or a ceiling,” and that the command’s focus was on capabilities, not fixed numbers.
But tensions have spilled into national security: an immigration raid at a Hyundai-LG battery plant in Georgia last year, threats to hike tariffs on South Korean goods to 25%, a reported partial restriction on intelligence sharing after a South Korean minister publicly identified a suspected North Korean nuclear site, and fallout from a U.S.-incorporated company’s data breach stalling talks on nuclear-powered submarines.
Behind the suburban veneer of Camp Humphreys is a military installation training for war. At the Vandal Training Center, soldiers run water-survival drills in a pool designed to simulate a helicopter crash. In a darkened medical room with artificial smoke and combat sounds, troops practice battlefield evacuations on $400,000 mannequins with severed limbs that bleed on command. Upstairs, VR simulators allow combat scenarios in almost any terrain. An official says the readiness standard is “fight tonight.”
For years, the focus has been across the northern border. North Korea has nuclear weapons and ballistic missiles capable of reaching the U.S. mainland. In late 2024, it deployed over 12,000 troops to support Russia in Ukraine and is believed to have received advanced military technology in return. But Washington is becoming more explicit about recalibrating the division of labor. The Pentagon’s January national defense strategy states that South Korea is capable of taking “primary responsibility” for deterring North Korea, with increasingly limited U.S. support.
Washington is also pushing to expand the mission beyond the peninsula. Camp Humphreys is roughly 800 km from Shanghai and under 1,400 km from Taiwan. “Korea sits at the center of the regional security geometry, with a positional advantage no other U.S. ally can replicate,” a USFK official said. Commander Xavier Brunson says the base “complicates every calculation” an adversary makes.
In Seoul, there are fears that hosting a launchpad for U.S. regional operations could drag South Korea into unwanted conflict with China. “Many South Koreans, particularly among more progressive constituencies, are reluctant to see USFK reoriented toward containing China,” says Jaechun Kim, a professor at Sogang University. “There is strong concern about entrapment in broader U.S.-China strategic competition, particularly over potential Taiwan contingencies.” Trump’s calls for allies to join U.S.-led operations in the Strait of Hormuz sharpened those concerns.
At Camp Humphreys, four new barracks are nearing completion, and a new elementary school is under construction. The base is going nowhere, and large-scale troop withdrawals remain unlikely. A sculpture outside USFK headquarters is inscribed on one side, in Korean: “함께 갑시다” (hamkke gapsida) - we go together. For now, at least, that’s the official line.