Not since the 1950s and the launch of the Soviet Sputnik has there been so much paranoia about mysterious flying objects over North America. Today, as then, geopolitical shifts have combined with rapid technological advances to leave the public feeling a deep unease. Shooting down an alleged Chinese spy balloon in North American airspace, as the US did on February 4, was unprecedented; the military has since downed three more unidentified objects. The discovery of the four craft has exposed gaps in surveillance and intelligence that must be addressed. But the US authorities should be wary of fanning a 1950s-style “red scare”.

US officials now say with high confidence that the balloon downed by a US fighter off South Carolina had been engaged in surveillance, and not weather research as Beijing asserted. The US military says it has recovered electronic components, including sensors, from the airship.

The origin and nature of the three objects shot down over Alaska, Canada’s Yukon, and Lake Huron at the weekend is still a mystery. US officials say all were smaller than the “spy” balloon and were at lower altitudes, and appeared to have no propulsion capabilities. Only the possibility they might be extraterrestrial — which lit up social media after a US general said he had “not ruled anything out” — has now been firmly denied.