When asked whether the U.S. had observed Russian spying on the crucial naval base, officials gave mixed signals.
"These actions are not designated towards any particular or individual effort of collection by the Russian government," one senior official said. "This is a holistic look at the Russian government's collection capabilities in the U.S. and the consulate in Seattle is just a particular location that has been designated."
Another official said that the Seattle consulate serves a role in Russia's intelligence collection in the U.S. but would not elaborate on any specific activities.
"We assess the Russian consulate in Seattle to be part of this broader problem of an unacceptably high number of Russian intelligence operatives in the United States," the official said.
"We think it sends a very clear signal, particularly since on the West Coast the Russians will have a degraded capability with regards to spying on our citizens," the official said.
Experts believe the base is home to the biggest concentration of nuclear weapons in the U.S., if not the world.
"In general, there will be two to three submarines in port with 200-300 weapons," Lisbeth Gronlund, co-director of the Global Security Program at the Union of Concerned Scientists, told CNBC. "There is also a storage center for nuclear weapons at the Bangor base that may hold several hundred additional warheads."
The Pentagon and U.S. Navy did not respond immediately to CNBC's request for comment.
In addition to its storage of strategic nuclear weapons, Kitsap-Bangor also serves as the homeport for more than half of the Navy's ballistic submarines — another significant interest to the Russian government. These stealthy Ohio-class submarines are undetectable launch pads for intercontinental missiles.
What's more, the number of submarines and other vessels berthed at Kitsap-Bangor makes the installation the third-largest fleet concentration in the United States.