The United States test-fired a submarine-launched ballistic missile capable of carrying nuclear warheads during a joint military exercise Wednesday with Saudi Arabia, a Western military official said.[Emphasis mine.] The whole thing really makes no sense. What may have happened is that a Trident missile was launched from a submarine, probably just off the U.S. coast as is normally done, and some Saudis were there to witness it. The AP writer heard about it, and made the assumption that they had brought a Trident missile to Saudi Arabia, set it up on land, and launched it.
The Trident missile launch was carried out in the kingdom, the official said, but he would not give a precise location. He spoke on condition of anonymity because of the sensitivity of the issue...
...A defense official in Washington confirmed the missile launch on condition of anonymity because he was not authorized to speak on the record. He said, however, that it took place late last week and was part of a demonstration.
The Western military official in the Saudi capital, Riyadh, said U.S. Lt. Gen. Patrick O'Reilly, head of the Missile Defense Agency, attended the test launch.
On the other hand, if we did really do a launch in the vicinity of the Arabian Peninsula, I'm not sure why we would launch one from land. However, if they brought a boomer into the Red Sea and launched from there, that would be impressive, and a good warning to the Iranians that they could never really ever win a war with the U.S.
Update 0930 01 Apr: Here's the denial that a missile launch happened. I didn't think the story made any sense.