China has insisted that the first balloon – which was high above Charlotte, North Carolina on Saturday evening – is just an errant civilian airship used mainly for meteorological research that went off course due to winds and has only limited “self-steering” capabilities.
That explanation has not been accepted by the US, and Mr Blinken called off a visit to Beijing, saying the incursion of the “surveillance asset” was “unacceptable” and “an irresponsible act.”
On Saturday, China hit back, saying that it “would not accept any groundless conjecture or hype” and accused “some politicians and media in the United States” of using the incident “as a pretext to attack and smear China.”
It urged the US to remain “cool-headed.”
The first balloon was spotted in the sky over Asheville, North Carolina on Saturday morning, moving over Charlotte in the afternoon.
Travelling at 46,000ft, the helium balloon with a payload the size of three buses, packed with instruments and sensors, is expected to continue east and could leave the continental US this weekend.
The second balloon was seen from the ground in Cartagena, northern Columbia and from Zulia state, in western Venezuela. There have been other unconfirmed sightings from Costa Rica.
Posting pictures of the foreign object, Venezuelan Meteorologist Oniel Castellanos said: “It is a white balloon that carries an antenna at the bottom and moves very slowly, at low altitude, from west to east.”