Graham told CNN he did not witness the incidents, but Australian pilots told him they were targeted multiple times by commercial lasers during South China Sea missions.
Graham was aboard HMAS Canberra, a helicopter landing dock and flagship of the Royal Australian Navy, as it operated in the South China Sea and Indian Ocean on a three-month mission that ended this week.
Australian forces across the region have noticed the increased use of lasers, an Australian Defense Department spokesperson said in a statement.
“The reason for vessels using the lasers is unknown, but it may be to draw attention to their presence in congested waterways,” the statement said.
At sea, fishermen are known to use lasers to warn off other vessels that may be getting too close to them.
“That makes sense for collision of vessels, but obviously there is no direct threat from aircraft to vessels in the South China Sea,” Graham said. “The maritime militia is, I think, not beyond argument as a tactic which is employed deliberately.”
Radio communications between the Australian and Chinese forces were courteous, Graham said.
CNN reached out to the Chinese Ministry of Defense but did not immediately hear back.
China has claimed almost the entire 1.3 million square mile South China Sea as its sovereign territory. In recent years it has aggressively asserted its stake in the face of conflicting claims from several Southeast Asian nations.
“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,” Graham said.
“The inappropriate use of lasers would pose a potential safety risk to all those operating in the region,” the Australian Department of Defense statement said.
No injuries were into Australian Navy pilots were reported from the recent incidents, the statement said.