Kuwait’s 91-year-old ruler Sheikh Sabah al-Ahmad Al-Sabah left for the United States Thursday morning to seek further medical treatment after recently undergoing surgery.

The statement did not elaborate on the nature of his illness, did not reveal on what type of surgery Sheikh Sabah had undergone in Kuwait, or what treatment was planned in the US.

The Emir Sheikh Sabah, a widely beloved ruler in this OPEC- member nation, took power since 2006, was hospitalized since this weekend.

The surgery took place on Sunday.

In September 2019, he underwent medical tests shortly after arriving in the US, leading to a meeting with President Trump being called off.

Sheikh Sabah had his appendix removed in 2002, two years after having a pacemaker fitted.

He had urinary tract surgery in the US in 2007.

Under Kuwaiti law, when the emir is absent, crown prince Sheikh Nawaf al-Ahmad Al-Sabah, 83, the emir’s half-brother, is appointed as acting ruler.

He is widely believed as the architect of modern Kuwait’s foreign policy.