Washington (CNN) The US Navy said Thursday that a Chinese military warship fired a military grade laser at US Navy P-8 surveillance aircraft last week while it was flying over the Pacific Ocean, an action that the US Navy called "unsafe and unprofessional."

The People's Republic of China "navy destroyer's actions were unsafe and unprofessional," US Pacific Fleet said in a statement Thursday.

"Weapons-grade lasers could potentially cause serious harm to aircrew and mariners, as well as ship and aircraft systems," the statement added.

Military-grade laser beams, occasionally known as "dazzlers," emit a powerful beam of light that can travel great distances and be used to illuminate aircraft cockpits, temporarily blinding pilots.

Defense officials told CNN that a formal diplomatic protests known as a démarche is expected to be issued.

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