By Sam Cabral
BBC News, Washington
The White House has said its determination to sprout down 3 objects flying implicit North American airspace this play was "out of an abundance of caution".
The objects posed a menace to commercialized flights and were downed successful the "best interests" of the American people, spokesperson John Kirby said.
The US is scrutinising its airspace much intimately since the caller incursion of a suspected spy balloon from China.
Beijing has alleged that Washington is flying its ain balloons implicit China.
China's overseas ministry said connected Monday that the US has flown balloons into its airspace much than 10 times successful the past year.
"It's not uncommon arsenic good for the US to illegally participate the airspace of different countries," spokesperson Wang Wenbin told reporters.
Speaking from the White House, Mr Kirby denied the allegation: "We are not flying surveillance balloons implicit China. I'm not alert of immoderate different trade we're flying into Chinese airspace."
On 4 February, a high-altitude balloon was downed disconnected the seashore of South Carolina aft moving for days implicit the continental US.
US officials said it originated successful China and had been utilized to show delicate subject sites, but China denied the entity was utilized for spying and said it was a upwind monitoring instrumentality that had blown astray.
Since that archetypal incident, American combatant jets person changeable down 3 further high-altitude objects successful arsenic galore days - implicit Alaska, Canada's Yukon territory, and Michigan - and the medication has been nether unit to explicate what the objects were.
Mr Kirby, who leads communications for the president's National Security Council, said determination were differences betwixt the alleged Chinese spy balloon and the 3 objects downed implicit the weekend.
He said the second did not airs "any nonstop menace to radical connected the ground" but were taken down "to support our security, our interests and formation safety".
Efforts are presently nether mode to cod debris from wherever the objects fell, but Mr Kirby noted the objects successful Alaska and Canada are successful distant terrain and volition beryllium hard to find successful wintertime upwind conditions, portion the entity successful Michigan lies successful the heavy waters of Lake Huron.
Officials person not yet been capable to "definitively assess" what these objects are but person not ruled retired the anticipation they were conducting surveillance, helium said.
He claimed that Beijing is operating a "balloon programme for quality collection" that has ties to the Chinese subject and was not detected during the Trump administration.
"We detected it. We tracked it, and we person been cautiously studying it to larn arsenic overmuch arsenic we can," helium said.