Saudi king will travel to US for treatment

Saudi Arabia's elderly King Abdullah flies to the US today for checks for a back ailment, and Crown Prince Sultan is returning from holiday. Political stability in the monarchy is of global concern. The Gulf Arab state controls more than a fifth of the world's crude reserves, is a vital US ally in the region, a major holder of dollar assets and home to the biggest Arab bourse.

Diplomats said the king's departure and the prince's sudden return indicate the kingdom, which has no elected parliament, is trying to prevent a power vacuum and reassure Washington and other allies.