In this May 2022 photo, Air Force Chief of Staff Gen. Charles Q. Brown testifies during the Senate Armed Services Committee hearing in Washington, DC.
CNN  — 

The nominee to be the US military’s most senior general warned US airmen in a letter this week that the Chinese military wants “to exploit your knowledge and skill to fill gaps in their military capability.”

Air Force Chief of Staff Gen. Charles Q. Brown, who has been nominated to replace Gen. Mark Milley as Chairman of the Joint Chiefs of Staff, said in the letter that foreign companies are “targeting and recruiting US and NATO-training military talent” to train China’s People’s Liberation Army.

“By essentially training the trainer, many of those who accept contracts with these foreign companies are eroding our national security, putting the very safety of their fellow servicemembers and the country at risk, and may be violating the law,” Brown said. “Just as I am asking for your help, I have also asked for help from our allied Air Chiefs to address the same issue within their ranks.”

“Protecting our national defense information is the responsibility of each servicemember and veteran,” he added.

The note from Brown was first reported by The Washington Post.

Concerns over western pilots training China’s military has grown in recent years, as Australia, the United Kingdom, and New Zealand – all members of the Five Eyes intelligence sharing alliance, which includes the US – have taken steps to prevent former military pilots from offering their expertise to Beijing.

Last October, the UK Ministry of Defense said it believed up to 30 former British military pilots were providing training in China and that many others have been approached, including pilots who were still serving.

“We are taking decisive steps to stop Chinese recruitment schemes attempting to headhunt serving and former UK Armed Forces pilots to train People’s Liberation Army personnel in the People’s Republic of China,” a ministry spokesperson said at the time.

One month later, Australia’s defense minister, Richard Marles, said reports of Australian pilots providing military training to China necessitated a review of current safety procedures because “Defense activities, people and assets are targets for Foreign Intelligence Services.”

A former US fighter pilot has also been indicted over allegations that he has been training Chinese pilots how to land on aircraft carriers – a skill he was taught in his own military training. He has denied the allegations, saying he was only training Chinese civilian pilots seeking to improve their skills. And recently, two Navy sailors were arrested and indicted for allegedly sending classified information to Chinese intelligence officers.