New York (CNN) -- King Abdullah of Saudi Arabia had successful follow-up back surgery in New York Friday, this time to stabilize several vertebrae in his spine, the official Saudi Press Agency reported, citing the Royal Court.
The monarch will soon begin a second round of physical therapy, the Royal Court said in a statement.
Abdullah first underwent successful surgery on November 24, according to a statement from the Saudi Royal Court.
The king is at New York Presbyterian Hospital / Weill Cornell Medical Center, hospital spokeswoman Kathy Robinson said Friday, though she would not elaborate.
The king traveled to the United States for treatment of a herniated spinal disc and a blood clot that was causing him back pain, Saudi state media reported.
Abdullah, 86, had named Crown Prince Sultan to administer the state's affairs in the monarch's absence, the state-run Saudi Press Agency reported at the time.
The top three figures in the kingdom -- Abdullah, Sultan and Prince Nayef, the country's interior minister and second deputy prime minister -- are all sons of King Abdul Aziz Ibn Saud, who founded modern Saudi Arabia in 1932.
Abdullah has ruled the oil-rich kingdom since the August 2005 death of his half-brother, King Fahd. But Abdullah ran most of the kingdom's affairs for a decade before that on behalf of his ailing half-brother.
Since coming to power, he has sought to establish rules and procedures for many Saudi institutions, giving him a reputation as a reformer in the highly conservative nation.