Remember when we thought we'd won Cold War?

No one ever expects the Russian nuclear submarine!

"It's the military trying to demonstrate that they are still a player in Russian political and economic matters," Mr. Polmar said.

One of the submarines is the newer Akula II, officials said, which is quieter than the older variant and the most advanced in the Russian fleet. The Akula is capable of carrying torpedoes for attacking other submarines and surface vessels as well as missiles for striking targets on land and at sea.

Defense Department officials declined to speculate on which weapons might be aboard the two submarines.

While the submarines have not taken any provocative action beyond their presence outside territorial waters of the United States, officials expressed wariness over the Kremlin's motivation for ordering such an unusual mission.

"Anytime the Russian Navy does something so out of the ordinary it is cause for worry," said a senior Defense Department official who has been monitoring reports on the submarines' activities.