Five Chinese navy ships are currently operating in the Bering Sea off the coast of Alaska, Pentagon officials said Wednesday, marking the first time the U.S. military has seen Chinese naval activity in the area.

The officials have been tracking the movements in recent days of three Chinese combat ships, a replenishment vessel and an amphibious landing ship after observing them moving toward the Aleutian Islands, which are split between U.S. and Russian control. (Latest News: Chinese Navy Ships Off Alaska Passed Through U.S. Territorial Waters)

“This would be a first in the vicinity of the Aleutian Islands,” one defense official said of the Chinese ships, which have been operating in international waters. “I don’t think we’d characterize anything they’re doing as threatening,” the official said.

A spokesman for the Chinese embassy in Washington couldn’t immediately be reached to comment.

Chinese officials have repeatedly demanded that the U.S. cease surveillance operations near China’s coast, and in May said Washington was meddling in their affairs by sending a military jet near a disputed chain of islands known as the Spratlys in the South China Sea.