President Joe Biden had a heated argument with Chinese President Xi Jinping over alleged biolabs in Ukraine, causing the U.S. president to lose “his cool,” according to a new book about the White House.

Biden and Xi had a conversation in March of 2022 after the U.S. gathered intelligence indicating that China was potentially going to supply Russia with arms during its war with Ukraine, according to Franklin Foer’s book, “The Last Politician: Inside Joe Biden’s White House and the Struggle for America’s Future.” After Biden warned Xi that providing Russia with arms would have consequences, the Chinese president pressed Biden on the potential presence of U.S. labs developing biological and chemical weapons in Ukraine, the book claims. (RELATED: Here’s Why Everyone Is Talking About Biolabs In Ukraine)

“You know better than that, this is crap,” Biden told Xi after he pressed about the biolabs. “Stop mouthing nonsense Russian talking points: I know you know that, so give me a break.”

Biden and Xi had kept the pretense that they “were old friends,” though tension between the two countries continues to grow, Foer writes. The interaction over Russia receiving Chinese supplies and alleged biolabs in Ukraine was the most heated argument the pair had ever had, the book claims.

Penguin Press, the publisher of Foer’s book, states that the book draws on “unparalleled access to the tight inner circle of advisers who have surrounded Biden for decades,” as Foer’s information predominately comes from anonymous sources. Foer notes in his book that he reports on Biden “from a close distance” through “several hundred interviews with his White House inner circle, his cabinet, his old friends and members of Congress.”

Former White House press secretary Jen Psaki and State Department spokesman Ned Price both denied the allegation that there were such labs in Ukraine. Dr. Robert Pope, head of the Pentagon’s Cooperative Threat Reduction Program (CTR), told the Daily Caller that the U.S. did not find biological weapons when the country first started working with Ukraine and hasn’t found any since. Russia’s unsubstantiated claims that Washington was developing biological weapons in Ukraine was often cited as a justification for the Kremlin to invade Ukraine in the early days of the war.

As tensions between the Chinese Communist Party (CCP) and the U.S. have risen, several Biden officials have visited China throughout the summer; Secretary of Commerce Gina Raimondo took a trip to China in August to meet with Chinese Minister of Culture and Tourism Hu Heping to discuss how the two countries can revive mutual tourism. Secretary of State Antony Blinken visited Beijing in June to meet with Xi, Central Foreign Affairs Office Director Wang Yi and Foreign Minister Qin Gang to propose military-to-military direct communication for crisis situations.