Bzzt. We do not sink ships in international waters without good and sufficient (i.e., readily demonstrated) cause.
The missile, naval in origin, would be perfect for land launch. Always ready for instant launch, always targeted, reliable, and protected in a silo. The nuke warhead would be the high maintenance part of the system.
Actually, the SS-N-6 is a "storable-liquid-fuel" missile with an evil reputation. It was the missile carried by that Yankee-class boat that blew up and sank off Bermuda in October 1986.
Actually, the "sinking the ship" part is easily covered.
"Oops! We're sorry. The CO of the USS Scorpion had NO IDEA that torpedo tube was LOADED."
Hard part would be keeping Rumsfeld from being TOO smug at the press briefing.
No problem then. They will blow up all on their own and sink. One thing, they might launch one missile, but then it would be over for them.