The Department of Defense has quietly delayed its cleanup of harmful “forever chemicals” at nearly 140 military installations across the country, according to a list of sites analyzed by The New York Times. The Pentagon has been one of the most intensive users of these chemicals, which are also known as PFAS and are a key ingredient in firefighting foam. In 2017, military communities nationwide began to report alarming levels of the chemicals in their drinking water. The Pentagon’s new timeline would delay cleanup around military sites by nearly a decade in some cases, according to the latest list, which is dated in March and was posted publicly in recent weeks without an announcement. They add up to a significant revision from the Pentagon’s earlier cleanup timetable, which had been released three months earlier, in December 2024, in the final days of the Biden administration.