Washington: White House National Security Council spokesman John Kirby on Monday (local time) confirmed that the Chinese spy balloon is linked to intelligence collection.

"China has a high-altitude balloon program for intelligence collection that's connected to the People's Liberation Army,"he said while addressing a press conference.

He said that the Chinese spy balloon program targeted the United States' "closest allies and partners," but provided "limited additive" intelligence collection capabilities.

"We assess at this time these balloons have provided limited additive capabilities to the PRC's other intelligence platforms used over the United States," Kirby said at the White House briefing.

"We know that these PRC surveillance balloons have crossed over dozens of countries including some of our allies and partners. We assessed that at this time these balloons have provided limited value to PRC's other intelligence platforms but could become more valuable in future," added Kirby.

He also confirmed that the US does not yet know who owns the recently shot-down unidentified objects.

Kirby also said that the same spy balloon programme was in operation during Donald Trump's Presidency, but his administration was not able to detect them like the Biden administration.

"It was operating during the previous administration but they did not detect it. We detected it. We tracked it," said the US NSC spokesperson while taking credit for finding the spy balloon.

Since shooting down the Chinese spy balloon off the coast of South Carolina on February 4, the United States has shot down three more unidentified flying objects, two in US airspace and one in Canadian airspace.

Kirby said that the three new objects were much smaller than the Chinese spy balloon and that the United States was still not sure what they might be.

"There is no question in our minds that that system was designed to surveil, that it was an intelligence asset," Kirby said of the Chinese spy balloon.

"We knew exactly what that thing was. These other three didn't have propulsion, they weren't being maneuvered, they were basically being driven by the wind. We don't know for sure whether they had a surveillance aspect to them but we can't rule it out."

Kirby said that the United States' apparent difficulty in tracking all four objects was owed to the nature of how radar is typically used and that the nation was enhancing its capabilities based on newly gathered intelligence.

"Slow-moving objects at high altitude with a small radar cross section are difficult to detect on radar, even objects as large as the Chinese spy balloon," Kirby said.

Kirby also vehemently rejected a Beijing accusation Monday that it had flown more than 10 high-altitude balloons over China.

"We are not flying surveillance balloons over China. I am not aware of any other craft that we are flying over into Chinese airspace," said the US NSC Coordinator for Strategic Communications.

He defended the decision to shoot down the three most recent objects despite the government not knowing what they were because they potentially posed a threat to civilian air traffic as they were flying at a similar altitude to many planes

The isolated and harsh conditions in the places they were shot down are hampering efforts to find debris to analyse, with the most recent of them likely in deep water in Lake Huron.