The abrupt decision came despite China’s claim that the balloon was a weather research “airship” that had blown off course. The U.S. has described it as a surveillance vehicle.

The development came just before Blinken had been due to depart Washington for Beijing and marked a new blow to already strained U.S.-Chinese relations.

President Joe Biden declined to comment when questioned at an economic event. Two 2024 reelection challengers, former President Donald Trump, and Nikki Haley, the former South Carolina governor and U.N. ambassador, said the U.S. should immediately shoot down the balloon.

Discovery of the balloon was announced by Pentagon officials who said one of the places it was spotted was over the state of Montana, which is home to one of America’s three nuclear missile silo fields at Malmstrom Air Force Base.

A senior defense official said the U.S. prepared fighter jets, including F-22s, to shoot down the balloon if ordered. The Pentagon ultimately recommended against it, noting that even as the balloon was over a sparsely populated area of Montana, its size would create a debris field large enough that it could have put people at risk.

The official said the balloon was headed over the Montana missile fields, but the U.S. has assessed that it had only “limited” value in terms of providing intelligence China couldn’t obtain by other technologies, such as spy satellites.

Blinken had been prepared as late as Thursday to travel to Beijing this weekend but the administration had begun to reconsider the trip following the discovery of the balloon on Wednesday, even before its presence was made public, an official said.

The official, who spoke to reporters on condition of anonymity due to the sensitivity of the matter, said the administration had “noted” China’s expression of regret.

The senior defense official did not address whether the U.S. accepted that it may have been a weather balloon instead of a surveillance one, as U.S. officials had previously described it. But, he said, the seriousness of the violation of U.S. airspace, sovereignty and international law was such that Blinken’s trip could not go forward as planned.

The official called the presence of the balloon “unacceptable” and said that message had been delivered by Blinken to Chinese State Councilor Wang Yi on Friday.

However, the official also said that Blinken had told the Chinese he would be prepared to travel to China “at the earliest opportunity when conditions allow.”

Blinken’s long-anticipated meetings with senior Chinese officials had been seen in both countries as a way to find some areas of common ground at a time of major disagreements over Taiwan, human rights, China’s claims in the South China Sea, North Korea, Russia’s war in Ukraine, trade policy and climate change.

Although the trip, which was agreed to in November by President Biden and Chinese President Xi Jinping at a summit in Indonesia, had not been formally announced, officials in both Beijing and Washington had been talking in recent days about Blinken’s imminent arrival.

The meetings were to begin on Sunday and go through Monday.

The discovery alarmed many in Washington across the country and, besides the U.S. protests lodged with Chinese official, it attracted strong criticism of the administration from Republican members of Congress who have advocating taking a tougher stance with China.

China, which angrily denounces surveillance attempts by the U.S. and others over areas it considers to be its territory and once forced down an American spy plane, offered a generally muted reaction to the Pentagon announcement.

In a relatively conciliatory statement, the Chinese foreign ministry said late Friday that the balloon was a civilian airship used mainly for meteorological research. The ministry said the airship has limited “self-steering” capabilities and “deviated far from its planned course” because of winds.

“The Chinese side regrets the unintended entry of the airship into U.S. airspace due to force majeure,” the statement said, citing a legal term used to refer to events beyond one’s control.