Did the US Test a Trident in Saudi Waters?

This story has been picked up around the Middle East though I'm a bit late to it: The Associated Press reported last week that the US had launched a Trident missile — yes, the submarine-launched ballistic missile that is the basis of the submarine-launched nuclear deterrent — in an exercise with Saudi Arabia.

The original AP story is here, sourced to an unnamed "Western military official" in Saudi Arabia and allegedly confirmed by an unnamed "defense official" in Washington.

The Pentagon just flat-out denied the story and it never seems to have gotten legs in the US. As this US Naval Institute blog post notes, there's something funny here, since the Trident is a pretty potent thing to be testing in Gulf waters or nearby. The story sounds rather fishy to me too; I know we're trying to reassure the Saudis about Iran, but launching a nuclear-capable intercontinental ballistic missile in Middle Eastern waters would be provocative to say the least. The denial seems more credible than the story at this point, which is probably why the story has sort of sunk from sight. It originally ran the middle of last week.

On the other hand, I imagine the story has been noticed in Tehran, which may have been the point all along.