The United States held briefings in Washington and Beijing with foreign diplomats from 40 nations about the Chinese spy balloon that entered US airspace in late January, a senior administration official and diplomats said on Tuesday.
US Deputy Secretary of State Wendy Sherman briefed nearly 150 foreign diplomats across 40 embassies on Monday, the official said, while in Beijing the US embassy gathered foreign diplomats on Monday and Tuesday to present US findings about the balloon.
"We want to make sure that we are sharing as much as we can with countries around the world who may also be susceptible to these types of operations," the senior administration official said.
Sherman's briefing was first reported by the Washington Post, which also quoted US officials saying the spy balloon was linked to an extensive military surveillance effort centered on China's Hainan Island in the South China Sea.
While analysts did not yet know the size of the Chinese balloon fleet, US officials spoke of dozens of missions since 2018 across five continents, with some targeting Japan, India, Vietnam, Taiwan and the Philippines.
The US State Department did not immediately respond to a request for comment.
Chinese military researchers have recently argued in publicly-available papers that balloons and airships should be further developed and deployed across a range of missions, Reuters reported on Monday.
The military operation involved technology from a private Chinese company that is part of China's military-civilian fusion apparatus, the Washington Post reported.
The appearance of the Chinese balloon over the United States last week caused political outrage in Washington and prompted US Secretary of State Antony Blinken to cancel a trip to Beijing that both countries had hoped would mend frayed relations. Blinken would have arrived in Beijing on Sunday.
A US Air Force fighter jet shot down the balloon off the South Carolina coast on Saturday, a week after it first entered US airspace.
China has said it was a weather balloon that had blown off course into U.S. airspace and was an "unexpected, isolated incident". It condemned the shoot-down and accused the United States of over-reacting.
The State Department also sent US missions around the world information about the balloon incident to share with allies and partners, the senior administration official added.
In the briefings in Beijing, the United States presented information to demonstrate that the balloon was not a weather research balloon as China said, but an airship that was used for espionage, said diplomats who attended the discussions.
Washington said the balloon was controlled by China's military, the People's Liberation Army.
Diplomats in Beijing said they were told by the US embassy that the solar panels on the balloon meant that it needed more power than a weather balloon, and that its flight path did not conform with natural wind patterns. US officials have said the balloon was equipped with rudders and propellers.
"Based on the US briefing, our own understanding about such balloons and the fact that China has so far refused to name the company or entity that owns this balloon, we find it hard to believe it is a civilian weather balloon," a Beijing-based Asian defense diplomat told Reuters.
Asked if Taiwan had been briefed by the United States, Taiwan's foreign ministry said in a statement to Reuters that "we have always maintained close contact with the United States and continue to exchange views on interactions between the United States and China."
The information was similar to what Pentagon has shared with reporters since the weekend, saying the balloons were part of a Chinese aerial fleet that has also violated the sovereignty of other countries.