(CNN) Fishermen off Norway's northern coast were astonished last week when they spotted a beluga whale wearing a harness, complete with mounts for a camera.

And according to marine experts, the mammal's backstory may be even stranger: They believe it was trained by the Russian military.

Experts believe a beluga whale spotted off the coast of Norway was trained by the Russian navy.

Fishermen Joar Hesten was the first to encounter the whale, off the coast of Finnmark, a county in northeastern Norway. Hesten then contacted the country's Directorate of Fisheries.

The whale was friendly and playful, witnesses said.

Jorgen Ree Wiig, a marine biologist at the directorate, told CNN: "The whale seemed playful but our instincts said that it was also asking for help to get out of the harness."

The harness appeared "specially made," Wiig said, and bore "mounts for GoPro cameras on each side of it," while the harness clips read "Equipment St. Petersburg."

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