The test of the hypersonic weapon, officially called the All-Up-Round AGM-183A Air-launched Rapid Response Weapon (ARRW), was conducted at the Reagan Test Site on Kwajalein Atoll in the Marshall Islands, almost 2,600 kilometers to the east of Guam, the statement said. Previous ARRW tests have been conducted off the US mainland. The ARRW consists of a rocket booster motor and the hypersonic glide vehicle, which carries a conventional warhead. 

Hypersonic glide vehicles travel at speeds greater than Mach 5, or approximately 4,000 miles per hour, making them difficult to detect and intercept in time. They can also maneuver and vary altitude, allowing them to evade current missile defense systems.