"There have been contacts made with the PRC on the high altitude balloon," Assistant Secretary of Defense Melissa Dalton told reporters, referring to the People's Republic of China.

US Defense Secretary Lloyd Austin asked to speak with Chinese counterparts shortly after an Air Force fighter shot down the Chinese balloon off the US east coast after it had traversed the entire country for days.

But he got no response, even though the incident prompted Secretary of State Antony Blinken to cancel a long-planned diplomatic mission to Beijing.

China said Thursday it refused the offer of a call with the US defense chief because of Washington's "irresponsible" decision to shoot down the balloon.

"This irresponsible and seriously mistaken approach by the US did not create a proper atmosphere for dialogue and exchanges between the two militaries," China's defense ministry said in a statement.

"The US insisted on using force to attack the airship, which seriously violated international practice and sets a bad precedent," it added.

Dalton, speaking after fighter jets downed the fourth suspicious object detected in US airspace in just over a week on Sunday, gave no details about who was involved in the contact or what they communicated.

While US officials say they are certain the Chinese balloon was in US airspace to collect intelligence, they have not characterized the subsequent three objects, saying they are smaller and did not particularly resemble the Chinese balloon.