Unidentified flying objects - timeline

4 February: US military shoots down suspected surveillance balloon off the coast of South Carolina. It had drifted for days over the US, and officials said it came from China and had been monitoring sensitive sites

10 February: US downs another object off northern Alaska which officials said lacked any system of propulsion or control

11 February: An American fighter jet shoots down a "high-altitude airborne object" over Canada's Yukon territory, about 100 miles (160 km) from the US border. It was described as cylindrical and smaller than the first balloon

12 February: US jets shoot down a fourth high-altitude object near Lake Huron "out of an abundance of caution"