Saudi Arabia’s king on Wednesday deposed the sitting crown prince, Mohammed bin Nayef, his 57-year-old nephew. He replaced him with Mohammed bin Salman bin Abdulaziz, the deputy crown prince.

Mohammed bin Salman, who is the son of King Salman, will now be the first in line to the throne when his father, 81, dies.

The 31-year-old has also been appointed deputy prime minister and will continue in his role as defense minister, according to a royal decree cited by state media.

Mohammed bin Salman has always had a visible role in the government, and has spearheaded the kingdom’s attempts to wean itself off oil as part of an economic strategy announced last year.

As defense minister, he also oversaw the Saudi-led military campaign against Yemen’s Houthi rebels.