KUWAIT CITY - Kuwait said its 91-year-old ruler has undergone successful surgery, without elaborating on what ails him, according to a report published on the state-run KUNA news agency on Sunday.
The Gulf nation has yet to elaborate on what required Sheikh Sabah Al Ahmad Al Sabah to seek a previously unannounced medical treatment on Saturday.
Sheikh Sabah's sudden surgery could inspire a renewed power struggle within Kuwait's ruling family. 
KUNA news agency had described Sheikh Sabah's hospitalisation on Saturday as "medical checks", citing a statement from the country's royal court.
Several hours later, KUNA published a second report saying 83-year-old Crown Prince Nawaf Al Ahmad Al Sabah had assumed some of Sheikh Sabah's powers temporarily, without explaining why that was necessary.
It has been a staunch US ally since the 1991 Gulf War expelled the occupying Iraqi forces of Saddam Hussein. Today, Kuwait hosts some 13,500 American troops, many at Camp Arifjan south of Kuwait City. (Aljazeera)