(Bloomberg) -- Beijing lashed out at President Joe Biden for saying Chinese leader Xi Jinping faces “enormous problems,” underscoring the renewed tensions between the two nations since the US downing of a balloon in its airspace.

“The US remarks are highly irresponsible and violate basic diplomatic protocols,” Chinese Foreign Ministry spokeswoman Mao Ning said Thursday at a regular press briefing in Beijing. “We are firmly opposed to that and condemn that,” Mao said in response to a question about Biden’s comments in an interview with PBS Newshour.

China’s Ministry of Defense said separately on Thursday it declined to engage in talks with the US over the balloon because “the use of force violates international practice and sets a bad precedent,” according to a statement from spokesman Tan Kefei. “The US hasn’t created a proper atmosphere for dialogue,” he added, calling the downing of what China considers a civilian balloon “irresponsible.”

The Pentagon earlier said China rebuffed US efforts to arrange a call between the two countries’ top defense officials. 

Read: Biden Denies US-China Ties More Strained After Balloon Spat

In an interview on Wednesday, Biden repeated comments he made in his State of the Union address that no world leader would want to trade places with Xi. Then he told interviewer Judy Woodruff that “this man has enormous problems.”

Biden said Xi has “great potential” but had “an economy that’s not functioning very well.” The US president also suggested Beijing’s ties with Moscow were a burden because of the war. “Everybody assumed that China would be all in with Russia and Ukraine. But they’re not all in it.”

Also: China Balloon Was Part of a Global Spying Effort, Blinken Says

Biden also denied that relations with Beijing have suffered a serious blow after the US downed what it said was a Chinese spy balloon that flew across the continental US. Mao hit back at an assertion by Secretary of State Antony Blinken that the high-altitude device was part of a years-long, global surveillance program run by Beijing.

She said she wasn’t aware of the specifics of Blinken’s claim, “but I think this may be part of the information warfare waged by the US against China. The international community knows clearly who the No. 1 spying and surveillance empire is.”

The aircraft was for civilian purposes, Mao reiterated, and strayed into the US due to weather conditions. Beijing has said the aircraft was a civilian climate research vehicle.

--With assistance from Rebecca Choong Wilkins, Lucille Liu and Michelle Fay Cortez.

(Adds comments from China’s Ministry of Defense in the third paragraph)

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