A suspected Chinese spy balloon flies above Charlotte, North Carolina, on Feb. 4, 2023. (Anadolu Agency/Getty/Kyodo)

The Chinese military unit in charge of outer space and cyber warfare was involved in the operation of a balloon that flew over the continental United States before being shot down by U.S. forces, several Chinese sources said Thursday.

China has maintained the balloon was being used for civilian weather research purposes. But a senior U.S. State Department official later in the day offered the most specific information to date on the incident, saying that the Chinese maker of the balloon has a "direct relationship" with the People's Liberation Army.

The official said the large balloon, equipped with multiple antennas and solar panels, was capable of conducting signals intelligence collection operations.

"(Its) equipment was clearly for intelligence surveillance and inconsistent with the equipment onboard weather balloons," the official said.

The Chinese military failed to notify the Foreign Ministry about its entry into U.S. airspace, prompting the leadership of President Xi Jinping to call for enhanced communications, according to the sources.

The reconnaissance balloon, developed by a space technology research unit under the government-affiliated Chinese Academy of Sciences, is designed to be used for both military and civilian purposes, but the unit is effectively led by the military, the sources said.

The unit has also flown spy balloons across the world, including in airspace over the Taiwan Strait and the South China Sea, they said.

The State Department official, who offered the details in a statement on condition of not being named, said the United States knows that China has flown such balloons over more than 40 countries across five continents.

According to the official, Washington will consider taking action against PLA-linked Chinese entities that helped the incursion into U.S. airspace, which was longer in duration than at least four similar cases in the past -- one at the start of the Biden administration and three during his predecessor Donald Trump's tenure.

Noting that China has given "no plausible explanation" for the balloon shot down Saturday by an F-22 fighter with a single missile off the coast of South Carolina, the official said its spy program will "only continue to be exposed, making it harder" for such activities to be carried out.

As both Democrats and Republicans are largely united when it comes to the threat of a rapidly rising China, the Biden administration is poised to adopt a tougher stance on Beijing.

On Thursday, the House of Representatives unanimously approved a resolution condemning China's use of the balloon over the United States, calling it a "brazen violation" of its sovereignty.

The resolution also accused the Chinese Communist Party of having attempted to "deceive the international community through false claims about its intelligence collection campaigns" and called on the Biden administration to keep Congress informed regarding the details of the incident.

In China, many space-related technologies are jointly developed and operated by the military and civilian sectors, but exactly how the technology is used often remains unclear.

On Feb. 2, the United States disclosed it was tracking what was believed to be a Chinese high-altitude surveillance balloon that had been flying over the country for days.

The Chinese Foreign Ministry said last Friday afternoon it was "gathering and verifying the facts," but claimed hours later that the balloon was a weather observation airship that unintentionally entered U.S. airspace, expressing regret over the incident.

The detection of the balloon by the United States led to Secretary of State Antony Blinken abruptly postponing his scheduled visit to Beijing until further notice.

China's leadership was alarmed by the seriousness of the unexpected development and has since required the balloon operator to obtain prior approval from Xi personally in situations where an airship may enter the airspace of other countries or regions during periods when there are important events on the diplomatic schedule, the sources said.

Alongside being the leader of China's ruling Communist Party, Xi is also the chief of the Central Military Commission which oversees the PLA.

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