What was the cargo ship, Arctic Sea, transporting, and why was it hijacked?

I grew up in Port Angeles, Washington. Port Angeles is located on the Olympic Peninsula, across the Strait of Juan de Fuca from Vancouver Island. The Strait of Juan de Fuca just happens to be the primary route to the Pacific Ocean from Naval Submarine Base Bangor, in nearby Bremerton. Bangor is one of two naval bases in the United States that houses America's fleet of Trident nuclear missile submarines.

A Russian cargo ship anchored itself in the middle of the strait about twelve years ago and just sat there without explaining themselves. The obvious explanation is that the Russians were probably counting submarines leaving and returning to Bangor. I suspect the Strait is shallow enough that it's not feasible for the submarines to leave the Strait submerged, and on fishing trips my dad and I saw one of them. Even surfaced, they are damn silent. I suppose they could have left Bangor through Canadian waters, though I don't know the political feasibility of sailing subs full of nuclear weapons through Canadian waters.

After the Russian cargo ship hung out in the strait for awhile, the American authorities figured they'd investigate it. So they got together with the Canadians and flew a helicopter over the ship. The ship evidently shone a laser at the helicopter (this is a couple of years before the days when lasers were an everyday cat toy) and blinded the American naval intelligence officer that was observing the ship. Investigating further, the Coast Guard decided to board the ship and search it for the laser. When they got around to boarding the ship, the laser was nowhere to be found. Eventually, the ship left the Strait.

I would think sinking would be the only way - unless ships transmit an explicit signal for radar to pick up.