According to The Wall Street Journal, Western allies are taking steps to discourage ex military pilots from working as instructors for Chinese military pilots, following reports of retired military personnel assisting China’s military.

After finishing an examination as to whether any retired Australian military members had joined the People’s Republic of China (PRC) to give services to the PRC military, Australian Defense Minister Richard Marles indicated Wednesday that the government will reassess national security standards. According to The Wall Street Journal, the United Kingdom called for similar measures in Oct. after the news appeared that several ex-Royal Air Force pilots actively assisted the Chinese military.

“It’s critical that we put the most robust system possible in place to defend Australia’s intelligence and secrets,” Marles said.

Marles confirmed rumors that persons approached veteran Australian defense officials on behalf of China, but did not clarify whether any advances were effective. The Australian Defense Department launched an initial investigation, which raised “enough concerns” for Marles to request a complete review of “rules and procedures that apply to our retired Defence personnel, especially all who come into possession of our country’s secret information.”

The Australian government is looking into “a number of situations,” according to Marles, but he refused to provide specific instances of Australian military members assisting China’s military.

According to the WSJ, the UK government laid out a range of initiatives, involving new national security laws, in Oct. to protect against additional PRC attempts to attract Western military personnel. According to The New York Times, China hired up to 18 highly proficient pilots who resigned from the British military to instruct fighters in the Chinese People’s Liberation Army.

According to a senior British diplomat, cases of ex-military pilots, many of whom piloted sophisticated fighter jets, working for the People’s Liberation Army have become more common in recent months, according to the New York Times. The official expressed concern that the practice may endanger the UK’s national security and stated that the UK was working with allies, a few of whom Beijing also has approached for hiring trainers.