President Donald Trump has boasted repeatedly about his big and powerful “nuclear button” — but according to a new report, it almost got away from him last year in China.

According to Axios, five sources said that on Nov. 9, during Trump’s visit to Beijing’s Great Hall of the People, Chief of Staff John Kelly and a U.S. Secret Service agent had a “skirmish” with Chinese security officials over the so-called nuclear “football,” which helps set a nuclear strike order in motion.

When the U.S. military aide carrying the football entered the Great Hall, Axios reported, Chinese security officials blocked his entry.

Kelly, in the adjoining room, was told, and the former United States Marine Corps general rushed over and told U.S. officials to keep walking, according to Axios.

“We’re moving in,” Kelly said — and his team all started moving.

A Chinese security official then grabbed Kelly, and Kelly shoved the man’s hand off of his body, according to Axios. Then a U.S. Secret Service agent grabbed that Chinese security official, and tackled him to the ground.

Axios reported that at no point did the Chinese have the nuclear football in their possession or even touch the briefcase.

The process for launching a nuclear strike is secret and complex. The nuclear football is carried by a rotating group of military officers everywhere the president goes and is equipped with communication tools and a book with prepared war plans.

If the president were to order a strike, he would identify himself to military officials at the Pentagon with codes unique to him. Those codes are recorded on a card known as the “biscuit” that is carried by the president at all times. He then would transmit the launch order to the Pentagon and Strategic Command.

The Associated Press contributed to this report.