The diplomatic row has escalated over the Chinese high-altitude balloon that flew across the US before being shot down, as the first wreckage was salvaged off the Atlantic coast. Beijing on Monday accused the US of “overreaction” and the “indiscriminate use of military force” in shooting down a Chinese balloon, warning of damage to bilateral relations. Joe Biden said that relations between Washington and Beijing had not been weakened by the incident, telling reporters: “We made it clear to China what we’re going to do. They understand our position. We’re not going to back off.” A state department spokesperson, Ned Price, pointed out that the secretary of state, Antony Blinken, had warned his counterpart, Wang Yi, on Friday that the US would take “appropriate actions to protect our interests”. “It should not have come as a complete surprise” to Beijing when the balloon was shot down the following day, Price said. If it had been a US airship over China, “you can only imagine the response from Beijing”, he added. The Pentagon said the first bits of debris had been found on the ocean surface off the South Carolina coast, while work continued to find the bits and pieces that had sunk to the sea bed. It called on the public to report any fragments that washed up on shore. The White House national security spokesperson, John Kirby, said the United States was able to study the balloon while it was flying and officials hope to glean valuable intelligence on its operations by retrieving as many components as possible. The head of North American Aerospace Defence (Norad) Command, General Glen VanHerck, described the balloon as being 200 feet (61 metres) high, with a surveillance payload the size of a regional passenger jet. When it was first spotted passing over the US Aleutian Islands, the general said he decided not to shoot it down. “It was my assessment that this balloon did not present a physical military threat to North America – this is under my Norad hat – and therefore, I could not take immediate action because it was not demonstrating hostile act or hostile intent,” VanHerck told reporters. He said the aircraft was able to manoeuvre to some extent by taking advantages of different wind directions at different altitudes, and that the balloon’s route appeared to have been deliberately planned to navigate those currents. China has claimed the aircraft was a weather balloon that had been blown off course. The country’s vice-foreign minister, Xie Feng, lodged a formal complaint with the US embassy on Sunday over the incident, accusing Washington of overreacting to an accident “caused by force majeure”, according to a statement posted on the Chinese foreign ministry website. “The facts are clear … but the United States turned a deaf ear and insisted on indiscriminate use of force against the civilian airship that was about to leave the United States airspace. It obviously overreacted and seriously violated the spirit of international law and international practice,” Xie was quoted as saying. He accused Washington of “dealing a serious blow” to efforts and progress in stabilising China-US relations since Joe Biden’s summit with Xi Jinping in November. “China resolutely opposes and strongly protests this, and urges the US to refrain from taking further actions to harm China’s interests and to escalate tensions,” he said. VanHerck said that an amphibious dock landing ship, the USS Carter Hall, would serve as the command vessel for the debris search, and that a navy oceanographic vessel was mapping below the surface to search for debris. Rough seas have hindered the search, but he said navy divers on rigid inflatable boats had begun work on Monday morning with the help of unmanned underwater vehicles, and that by the afternoon, more would be known about the location of large pieces of submerged debris. The incident came amid tensions over issues including Taiwan, trade and human rights. It also prompted Antony Blinken, the US secretary of state, to postpone a visit to Beijing. On Monday, the Chinese foreign ministry spokesperson Mao Ning said the incident tested “the US’s sincerity in stabilising and improving Sino-US relations”. She said: “The US deliberately exaggerated and hyped [the incident] and even used military force to attack. This is unacceptable and irresponsible.” She also admitted that the balloon spotted over Latin America belonged to China but said it was a civilian airship used for flight tests that entered the airspace of Latin America and the Caribbean “by accident”. Yoshihiko Isozaki, the Japanese deputy chief cabinet secretary, said on Monday that a flying object thought to be Chinese and similar to the one shot down by the US, had been spotted at least twice over northern Japan since 2020, the Associated Press reported. China has previously objected when foreign military surveillance planes flew off its coast in international airspace. In 2001, a US navy plane conducting routine surveillance near the Chinese coast collided with a Chinese fighter plane, killing the Chinese fighter pilot and damaging the American plane, which was forced to make an emergency landing at a Chinese naval airbase on the southern island of Hainan. China detained the 24-member US navy aircrew for 10 days until the US expressed regret. Prof William Hurst, the deputy director at the Centre for Geopolitics at the University of Cambridge, said the balloon incident had occurred in a much more negative climate than the spy plane incident. “The public revelation complicated domestic politics in the US, which were already fraught,” he said. “Its effect will likely be smaller, but take longer to unwind.” VanHerck, the Norad chief, said the military had not detected previous spy balloons before this one and called it an “awareness gap.” However, he said US intelligence determined previous flights after the fact based on “additional means of collection” of intelligence.