According to Jonathan Swan of Axios, last November 9, when President Trump was joined by Chief of Staff John Kelly and a U.S. military aide who carried the “nuclear football” as they visited Chinese leaders in Beijing, Chinese security officials blocked the aide from entering Great Hall of the People, prompting Kelly to protest, a Chinese security official to grab Kelly, and a Secret Service agent to tackle the Chinese security official to the ground.

As Bill Gulley, the former director of the White House Military Office, has written:

There are four things in the Football. The Black Book containing the retaliatory options, a book listing classified site locations, a manila folder with eight or ten pages stapled together giving a description of procedures for the Emergency Alert System, and a three-by-five inch card with authentication codes. The Black Book was about 9 by 12 inches and had 75 loose-leaf pages printed in black and red. The book with classified site locations was about the same size as the Black Book, and was black. It contained information on sites around the country where the president could be taken in an emergency.

Swan cited five separate sources who confirmed his story. Swan reported that after the military aide was blocked:

A U.S. official hurried into the adjoining room and told Kelly what was happening. Kelly rushed over and told the U.S. officials to keep walking — "We're moving in," he said — and the Americans all started moving. Then there was a commotion. A Chinese security official grabbed Kelly, and Kelly shoved the man’s hand off of his body. Then a U.S. Secret Service agent grabbed the Chinese security official and tackled him to the ground.

Swan added that U.S. officials were instructed to remain silent about the matter; he also noted that Trump’s team had briefed the Chinese about the normal protocol before the visit.

Swan wrote, “I'm told that at no point did the Chinese have the nuclear football in their possession or even touch the briefcase. I'm also told the head of the Chinese security detail apologized to the Americans afterwards for the misunderstanding.”

The “nuclear biscuit” is the card with the launch codes that resides in the briefcases. President Bill Clinton reportedly lost it for a time in 2000.