Prior Chinese Balloon Incursions Over U.S. Went Undetected, Officials Say

Those previous balloon flights were much shorter in duration, possibly explaining why some went undetected at the time, the senior administration officials said. One official said that much of the information on the flights was pieced together later.

“This information was discovered after the prior administration left,” one of the officials said. The official said that intelligence agencies are preparing to brief key figures in the previous Trump administration.

Emerging details about the extent of China’s balloon surveillance program are raising questions about why the government wasn’t better prepared to deflect the most recent incursion and how the U.S. handled the previous four instances.

Some Republican lawmakers said, given the reports of prior incursions, that the Biden administration should have shot down the balloon before it entered the continental U.S. After being spotted above Alaska’s Aleutian Islands on Jan. 28, the balloon traveled over the state and then Canada, reaching northern Idaho on Jan. 31. From there it passed over intercontinental ballistic missile sites in Montana, before drifting to the Southeast coast.

“This administration didn’t just fail here. They failed to prepare after the first time this happened during this administration,” Rep.

Mike Turner

(R., Ohio), chairman of the House Intelligence Committee, said Sunday on NBC’s “Meet the Press.” He added, “The president allowed this to go across our most sensitive sites.”

The administration said that waiting until the balloon was off the coast to shoot it down was prudent, enabling the U.S. to retrieve the surveillance equipment without endangering people who might have been struck by debris.

“Our No. 1 concern was how could we take this down without creating undue risk to people or property on the ground,” a senior defense official said Saturday.

The presence of the balloon and its downing raised already high tensions with Beijing and complicated efforts to manage the two powers’ fractious rivalry. On Friday, Secretary of State

Antony Blinken

postponed a trip to Beijing that both governments sought to stabilize relations strained over Taiwan, U.S. technology controls and Beijing’s ties with Russia during its Ukraine war.

In the wake of the shootdown, Beijing criticized the U.S., though in tones more modulated than in previous crises, such as over Taiwan.

China’s Foreign Ministry reiterated claims that the craft was for civilian meteorological research and had blown off course. It called the decision to bring down the balloon a “serious violation of international practice,” while saying Beijing “reserves the right to make further responses if necessary.” China’s Defense Ministry issued a similar comment, calling the shootdown an “obvious overreaction.”

Having downed the balloon, the U.S. military is trying to retrieve its remains from coastal waters about 47-feet deep and learn more about the surveillance capabilities. A half-dozen Navy and Coast Guard vessels were involved in the recovery mission.

As of Sunday afternoon, no major pieces of the craft had been collected from what a U.S. defense official said was a “very large” debris field. The ships are cordoning off the majority of that area, the official said.

The previous breaches that have come to light—and that Biden administration officials say have been undetected until after they occurred—have underscored concerns about the robustness of the U.S. and Canadian network of ground-based radars to identify aerial threats. The Pentagon said this weekend that China has a fleet of surveillance balloons spotted previously over Latin America, Europe and Asia.

Several of the Trump administration’s top national security officials said that they were never made aware of any ongoing or previous balloon breaches.

“I had no knowledge of any incursions into U.S. airspace as national security adviser, either during my time as national security adviser or before I got there, nor was I briefed on any China issues like this,” said Robert O’Brien, who served as Mr. Trump’s last national security adviser from 2019 to 2021.

John Bolton

and H.R. McMaster, Mr. O’Brien’s predecessors as national security adviser, also said that they were never informed of any balloon breaches.

The Biden administration officials declined to elaborate on how the breaches were subsequently detected, citing the need to protect intelligence methods.

The three breaches during the Trump administration were brief, one of the officials said, while the other instance occurred early in the Biden administration.

On Saturday, the defense official said that in the previous instances the Chinese balloons “transited the continental U.S. briefly” and for not nearly as long as the most recent balloon. At least one of those earlier intrusions was in 2019, other officials said.

Senate Majority Leader

Chuck Schumer

(D., N.Y.), while applauding the administration’s handling of the balloon, said Sunday that the full Senate will receive a classified briefing on Feb. 15 about the incident and Chinese surveillance. Mr. Schumer said knowledge of how these balloons operate has grown in the past year, and that collection of the downed balloon will help to advance their understanding.

The Office of the Director of National Intelligence, the oversight body for the nation’s intelligence community, didn’t immediately respond to questions about what was known about the previous balloon incidents or when they were detected. NORAD, the North American Aerospace Command, also didn’t immediately respond to a request for comment.

After the balloon was first detected on Jan. 28 when it was near and then over Alaska, the question of shooting it down was raised at the White House, according to one of the senior administration officials, but the decision was for NORAD, to track the balloon and learn what it could about its capabilities.

NORAD, which is run jointly by the U.S. and Canada, continued tracking the balloon as it crossed over Canada on Jan. 30.

By Tuesday, Jan. 31, when the craft was over northern Idaho, Mr. Biden directed the Pentagon to shield sensitive sites from the surveillance balloon and to present options to shoot it down right away.

On Wednesday, the Pentagon said it was too risky to down the balloon over land if it might hurt people below and it was decided the U.S. military would shoot it down as soon as it was over the U.S. territorial waters, administration officials.

Advanced modeling was conducted to determine the size of any potential debris field. Some projections showed that if a missile shot a hole in the balloon but didn’t explode, the craft could begin a slow descent and could land anywhere within a swath of several hundred miles, according to a U.S. official.

On Friday night, Mr. Biden approved the final plan for an Air Force F-22 jet fighter to shoot down the balloon with an AIM-9X Sidewinder missile and for U.S. naval assets to recover the surveillance equipment.

“We have F-22s on alert in Alaska,” said David Deptula, the dean of the Mitchell Institute for Aerospace Studies and a retired Air Force three-star general. “I believe that it should have been shot down in U.S. airspace prior to overflying U.S. territory.”

—Nancy A. Youssef and Gordon Lubold contributed to this article.

Write to Vivian Salama at vivian.salama@wsj.com and Michael R. Gordon at michael.gordon@wsj.com