A Russian intelligence vessel this week sailed near one of the drill rigs that Royal Dutch Shell is using in the Chukchi Sea, according to a CNN report.
The ship, the Kurily, was sailing in international waters when it passed near the Shell-contracted Noble Discoverer, the CNN report said.
A Pentagon spokesman told CNN that the ship had the right to be in that area and that no U.S. defense assets were deployed in response to its presence.
The ship's presence did not disrupt the drilling being done by the Shell-hired Polar Pioneer or any other Shell activities, a company spokeswoman said.
"We were aware of this ship," spokeswoman Megan Baldino said. "It did not have any impact on our operations."
Shell monitors vessel traffic and other conditions in the area where it is drilling, so company officials knew of the Russian vessel, Baldino said.
Hundreds of ships from a variety of nations were sailing Tuesday in the waters north of the Aleutian Islands, according to organizations that track vessel traffic.
More than 300 large ships bearing flags of countries including Korea, Canada, Norway, Panama, Bermuda and the Marshall Islands, among others, were in the U.S. exclusive economic zone of the Bering and Chukchi seas, said Steven Gabelein of the Juneau-based Marine Exchange of Alaska.
That does not include relatively small fishing vessels because the exchange tracks only large ships that carry identifying equipment, he said.