Story highlights The Chinese ships were doing operations "consistent with international law," U.S. officials told CNN

This is a first for Chinese naval ships -- and the transit took place while President Barack Obama was in Alaska

(CNN) Chinese navy ships entered U.S. territorial waters off of Alaska last week, coming within 12 miles of the coastline, multiple defense officials told CNN on Friday.

The Chinese ships were doing operations "consistent with international law," U.S. officials said, under the maritime rule of "innocent passage," where ships are permitted to enter territorial waters and are not challenged so long as they keep moving directly and expeditiously.

U.S. officials emphasized that Russian warships exercise "innocent passage" around Alaska with regularity. However, this is a first for Chinese naval ships -- and the transit took place while President Barack Obama was in Alaska.

U.S. Northern Command, whose area of responsibility includes all air, land and sea approaches to the continental U.S. and Alaska, told CNN it is not aware of any communications between the U.S. and Chinese military during the passage.

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