The United States is recovering debris from the downed Chinese balloon in the Atlantic for analysis by intelligence experts and there is no plan to give the remains back to Beijing, officials said Monday.

China says the balloon was an errant weather observation aircraft with no military purpose, but the United States says it was a sophisticated high-altitude spying vehicle.

"They have recovered some remnants off the surface of the sea and weather conditions did not permit much undersea surveillance of the debris field," US National Security Council spokesman John Kirby said two days after a US fighter jet shot down the balloon.

US personnel will "in the coming days be able to get down there and take a better look at what's on the bottom of the ocean, but it's just started," Kirby said.

General Glen VanHerck, head of the US Northern Command, separately told reporters that a Navy ship is in the process of mapping the debris field, which is expected to measure about 1,500 by 1,500 meters (yards).

The balloon itself was up to 200 feet (60 meters) tall and carried a payload weighing several thousand pounds that was roughly the size of a regional jet aircraft, he said.

After slowly traversing the middle of the United States, reportedly over several top secret military sites, the balloon headed out over the east coast, where President Joe Biden ordered it to be shot down.

Kirby said there was no intention to send the pieces back. "I know of no such intention or plans to return it," he said.

VanHerck said the balloon debris would be carefully studied.

"I don't know where the debris is going to go for a final analysis, but I will tell you that certainly, the intel community along with the law enforcement community that works this under counterintelligence will take a good look at it," he said.

The Biden administration is painting the incident as a provocative move by China that turned into something of its own goal by providing US intelligence services with valuable data.

According to Kirby, measures were taken to ensure the balloon's instruments were "mitigated" in their ability to spy, while "at the same time increasing and improving our ability to collect intelligence and information from it."

"We're still analyzing the information that we were able to collect off of the balloon before we shot it out of the sky and now we're going to recover it and I suspect we may learn even more."

One detail already known, Kirby said, is that the balloon was not merely drifting but had propellers and steering to give a measure of control, even as it was swept along in the high-altitude Jet Stream wind.

"It is true that this balloon had the ability manoeuvre itself -- to speed up, to slow down and to turn. So it had propellers, it had a rudder, if you will, to allow it to change direction," he said. "But the most important navigational vector was the jet stream itself, the winds at such a high altitude."