The U.S. government said Tuesday that so far it has no evidence that the three airborne objects it shot down last weekend over North America were linked to China or any other foreign spy program.

U.S. investigators “thus far haven't seen any indication or anything that points specifically to the idea that these three objects were part of [China’s] spy balloon program or that they were definitely involved in external intelligence collection efforts,” National Security Council spokesman John Kirby told reporters at the White House.

Kirby said the three objects — two shot down over the United States and one over Canada — "could be balloons that were simply tied to commercial or research entities and therefore benign."

Nonetheless, Kirby contended that China is running a "well-funded, deliberate program" to use high-altitude, hard-to-detect balloons for spying on the United States and other countries. American officials say a fighter jet shot down such a balloon on February 4 off the southeastern U.S. coast after allowing it to traverse the U.S. mainland for eight days.

China has continued to claim that the errant balloon was gathering weather information and drifted over the U.S. by mistake. But U.S. officials say they have recovered parts of it and concluded it was on a sophisticated surveillance mission over U.S. military bases.

The incident triggered heightened U.S. radar scanning for other airborne objects and the subsequent shootdown of one object over frozen waters near the northwestern-most U.S. state of Alaska, another over Canada’s Yukon territory and a third over Lake Huron that straddles the U.S.-Canada border.

The Chinese spy balloon and the next two objects were each downed with a single missile strike, officials said, but the first missile shot missed the object over Lake Huron before a second missile downed it.

Kirby said “pretty tough” weather and geographical conditions near where all three of the downed balloons or airborne objects were hit last weekend is making it harder to find the debris.

“We’re recognizing that it could be some time before we locate and recover the debris," he said. "We haven't found them yet."

On Monday, Kirby said the U.S. does not know the origin of the three high-altitude objects it shot down.

“They didn’t have propulsion,” he said. “They were not being maneuvered. They didn’t have surveillance [capability], but we couldn’t rule it out.”

“We’re sort of in uncharted territory here,” Kirby said. He said they were shot down because they posed a threat to civilian aircraft, unlike the Chinese spy balloon that was flying at a much higher altitude.

While the search continues for the objects shot down last weekend, the U.S. military’s Northern Command said in a statement Monday that crews working to find parts of the spy balloon in the Atlantic Ocean had recovered “significant debris from the site, including all of the priority sensor and electronics pieces identified as well as large sections of the structure.”

(SJ/VOA)