The U.S. has detected and is monitoring a suspected Chinese high-altitude surveillance balloon that has been hovering over the country for several days. The balloon is said to typically operate at 80,000-120,000 feet (24,000-37,000 meters), compared to 33,000 and 42,000 feet (10,000-12,800 meters) for commercial aircraft. The U.S. is angry about the balloon and is taking measures to protect against foreign intelligence collection of sensitive information.