Minuteman III intercontinental ballistic missile (ICBM), recently seen in the news, developed by which country?

The US tested an unarmed Minuteman III ICBM from Vandenberg Space Force Base. The Minuteman III, deployed in the 1960s, is the sole land-based component of the US nuclear triad, designed by Boeing. Despite initial plans for a ten-year service, it will be used until the GBSD is available in 2029. The three-stage, solid-fuel missile, with a 13,000 km range, currently carries a single nuclear warhead, ensuring fast launch and high reliability.