It looks like Russian attack boats Akula class according to reports, are patrolling off of the US coast.
The military says that they are not concerned, and that they tracked them all the way here:
Two nuclear-powered Russian attack submarines have been patrolling off the eastern seaboard of the United States in the first mission of its kind so close to shore in nearly a decade, U.S. officials said on Wednesday.
The Pentagon said it was not alarmed by the maneuvers, carried out by what officials described as Soviet-designed Akula-class submarines in international waters as little as 200 miles off the coast.
Interesting in all this is the rather matter of fact statement that there was no problem tracking the boats:
The official said the Navy was able to track the submarines as they made their way through international waters off the American coastline. This can be done from aircraft, ships, underwater sensors or other submarines.
It makes me wonder if this was not intended to be public in the first place. The Russians have already leased a sub to India, and there are other potential customers, and patrolling off the US coast, if it makes it into the papers, is an advertisement for the product.
The Akulas may not be Virginia class boats, but they are pretty quiet, after all.
Then again, maybe they just wanted some good cigars, as some of the reports note that at least one of the boats paid a visit to Cuba.