Two Russian Project 971 submarines (known as Akula-class in the U.S.) spotted off the U.S. Eastern coast have people scratching their heads - Why would Russia send its submarines there?

U.S. submarines, of course, patrol close to Russian waters all the time[*], but at least they have a mission of sort - to shadow Russian ballistic missile subs as they go to their (infrequent) patrols or missile tests (which is, by the way, a rather dangerous practice that is hardly justified these days). Since Russian boomers rarely stray far from their bases (although they do occasionally), it makes certain sense for the U.S. attack submarines to spend their time somewhere near the Barents Sea.

But it doesn't really make sense for Russian submarines to go to the U.S. coast - there is no one there. The only reason to be there would be to show the flag, but with submarines you show the flag by not showing up on sonar screens - the point is to avoid detection. But I guess these mission could always be justified by crew training and things like that.

For some reason, "Defense Department officials declined to speculate on which weapons might be aboard the two submarines". As I understand, there should be no uncertainty there - START Treaty requires the United States and Russia to exchange declarations about nuclear SLCMs carried by their attack submarines (Note: one more reason to keep START in force). These are not released publicly, but the U.S. governments would probably know what's in them.

UPDATE 08/05/09: NORAD and the Northern Command issued a brief statement (emphasis added):

NORAD and US Northern Command are aware of Russian submarine activity off the East coast operating in international waters. We have been monitoring them during transit and recognize the right of all nations to exercise freedom of navigation in international waters according to international law.

Again, I'm not saying that Russia should not let its submarines to go on patrol or that U.S. submarine patrols are somehow more legitimate. The point is that there is no particularly useful mission in those patrols (whether U.S. or Russian).

UPDATE 08/06/09: As a reader correctly noted, the linked post at the FAS site describes patrols of strategic submarines, which do not go close to the Russian waters. U.S. attack submarines, however, do have a mission of shadowing Russian submarines. As far as I understands, they do come very close to the Russian waters (if only because Russian subs don't go very far very often).