On February 2, 2023 North American Aerospace Defence Command (NORAD) issued a press release indicating that NORAD and US Northern Command detected and is tracking a high altitude surveillance balloon over the continental United States. The NORAD commander, General VanHerk stated that the balloon does not present a threat to persons on the ground. The balloon is travelling well above commercial air traffic.
Wikipedia has more details about the balloon captured from open media sources. It reports that the balloon at an altitude of 24,000 and 37,000 meters (79,000 and 121,000 ft). It passed over the Aleutian Islands (Alaska) and Canada. It is a large balloon with a technology bay. The vessel is about the size of 3 buses. An AWACS (Boeing E-3 Sentry) and F-22 Raptor aircraft sent by NORAD are monitoring the balloon.
Balloon experiments in amateur radio are common (see also https://en.wikipedia.org/wiki/High-altitude_balloon ). Above is an image of the Earth's horizon taken from 26 km on one of these flights. While the Yellowknife Amateur Radio Society has not engaged in such experiments, it is on our list of projects to explore. We have monitored high altitude balloons passing over the Northwest Territories and their telemetry but those balloons were amateur radio experiments, not military.