Australian navy helicopter pilots were hit with laser beams from fishing boats during military exercises in the South China Sea in May 2019, an analyst who was observing Australia’s operations said.
Euan Graham, an Asian security expert at Melbourne’s La Trobe University, was observing the Royal Australian Navy’s operation from on board the HMAS Canberra, a helicopter docking vessel, and said that Australia’s helicopters were being targeted with lasers from fishing boats.
He wrote for the Australian Strategic Policy Institute, a think tank, that the lasers pointed at the helicopters led to “temporarily grounding them for precautionary medical reasons.”
Graham posited that the boats where the lasers originated could be Chinese: “Was this startled fishermen reacting to the unexpected? Or was it the sort of coordinated harassment more suggestive of China’s maritime militia?”
Graham noted to CNN that: “It’s no secret that the broader thrust of China’s approach in the South China Sea is to try to make life difficult for foreign aircraft and warships there.”
China claims the South China Sea, despite competing claims and legal disputes from other countries in the region.
He said that it was unlikely to be fishermen using lasers to warn the helicopters away as there was little chance that a helicopter and a boat would be on course to collide.
“That makes sense for collision of vessels, but obviously there is no direct threat from aircraft to vessels in the South China Sea,” he said. “The maritime militia is, I think, not beyond argument as a tactic which is employed deliberately.”
Reports in 2018 said that more than 20 attacks with lasers were made against US military pilots in the East China Sea between September 2017 and June 2018.
Graham told CNN that he did not witness the lasers first hand, but pilots told him that they were repeatedly targeted.
He said in the post for the Australian Strategic Policy Institute that the Australian navy was “followed at a discreet distance by a Chinese warship for most of the transit, both on the way up and back, despite the fact that our route didn’t take us near any feature occupied by Chinese forces, or any obviously sensitive areas.”
The HMAS Canberra at sea in 2016.
China claims the vast majority of the South China Sea as its own despite protests and legal battles with other countries in the region. It is a key transportation route for nations in the region, and contains oil and gas reserves. China has staked its territorial claims in recent years by creating manmade islands in the area, some of which are home to airfields.
Graham said said that radio communications between the Chinese and Australian navys was “courteous” during his time with the operation.
Australia’s military was conducting its Indo-Pacific Endeavour 2019 exercise, which concluded this week. The 11-week operation brought the military to Malaysia, Singapore, Thailand, Vietnam, India, Sri Lanka, and Indonesia to share disaster relief expertise.
Officials from Australia’s military told CNN that they were looking into Graham’s claims.
This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.