President Joe Biden said Wednesday the United States is not looking for conflict with China despite heightened tensions over last week's downing of a Chinese balloon that US officials say was part of a spy fleet spanning five continents.

"We're going to compete fully with China, but... we're not looking for conflict -- and that's been the case so far," he said in a televised interview with PBS.

Pointing to global ramifications of the balloon incident that has animated the United States, Secretary of State Antony Blinken said earlier that the United States was giving data to allies as it assesses recovered debris.

"We already shared information with dozens of countries around the world, both from Washington and through our embassies," Blinken said.

"We're doing so because the United States was not the only target of this broader program, which has violated the sovereignty of countries across five continents," he told a joint news conference with NATO chief Jens Stoltenberg.

White House Press Secretary Karine Jean-Pierre, speaking separately to reporters on Air Force One, described the balloons as part of a fleet and said they had been spotted around the world for several years.

A huge white balloon carrying sophisticated equipment traversed the continental United States last week before Biden ordered the military to shoot it down just off the east coast in the Atlantic.

China insists that the balloon was merely conducting weather research, but the Pentagon described it as a high-tech spying operation. The balloon floated at an altitude far higher than most airplanes and crossed directly over at least one sensitive US military site.

The NATO secretary-general, whose visit to Washington followed a trip to Japan and South Korea, said the balloon showed the need for countries across the alliance to protect themselves.

"The Chinese balloon over the United States confirms a pattern of Chinese behavior where we see that China over the last years has invested heavily in new military capabilities," Stoltenberg said.

"We've also seen increased Chinese intelligence activities in Europe. They use satellites, they use cyber and, as we've seen over the United States, also balloons. So we just have to be vigilant," he said.

Stoltenberg also issued a new warning that China was drawing lessons from the war in Ukraine, which NATO countries have been supporting as it fights back Russian invaders.

"What happens in Europe today could happen in Asia tomorrow," Stoltenberg said, pointing to China's pressure on Taiwan, the self-governing democracy claimed by Beijing.

The Washington Post, quoting US officials, reported that the Chinese surveillance program has been run partly out of the southern island of Hainan.

Updating old technology, the balloons have been used to monitor the military assets of nearby rivals such as Japan, India and Taiwan, the newspaper said.

Biden, in his State of the Union address on Tuesday, said that his orders to shoot down the balloon showed that the United States would not hesitate to act when needed.

But he also stressed that the United States did not want conflict with China. The balloon episode led Blinken to postpone a trip to China in which he had hoped to work at easing tensions.

China, which voiced regret about the air intrusion but later denounced the US decision to down it, responded to Biden that it would also "firmly defend" its interests.

US officials said they took measures to prevent the balloon's instruments from collecting confidential information during its flight.

They say that the decision to wait until the balloon reached water was the only way to ensure the safety of people on the ground.

Biden's Republican rivals say he should have ordered the balloon to be destroyed as soon as it was identified.

(AFP)

This picture provided by the US Navy shows sailors assigned to Explosive Ordnance Disposal Group 2 recover a high-altitude surveillance balloon off the coast of Myrtle Beach, South Carolina, in the Atlantic Ocean on February 5, 2023. (AFP)

Biden says US not seeking conflict with China, despite balloon flap