Saudi King Salman bin Abdulaziz has replaced his younger half-brother Moqren bin Abdul Aziz bin Saud with his nephew, Mohammed bin Nayef, who is the current interior minister, as the new crown prince and the first in line to take over the throne. The move marks the first time a grandson of the founder has been named the crown prince.

Moqren, who is the youngest son of Saudi Arabia’s founder King Abdulaziz ibn Saud, will be replaced by bin Nayef, 55, who is the grandson of the founder of the world’s largest oil exporter. In the decision, announced early Wednesday, Salman also named his son, Prince Mohammed bin Salman, who is the current defense minister, as the deputy crown prince of the oil-rich nation. 

“These are serious changes that will have repercussions not only domestically but also internationally,” Khalil Jahshan, the executive director for the Arab Center of Washington, told Al Jazeera. “This is a very decisive answer by King Salman to the doubts that many experts have expressed since he came into power with regards to his health, his decisiveness and his control over political matters in the kingdom.”

Salman, 79, came to power in January after the death of his half-brother King Abdullah bin Abdulaziz. Moqren’s dismissal removes the last high-level official continuing since the reign of King Abdullah. Bin Nayef’s appointment also reasserts control of the so-called “Sudairi Seven” -- an alliance of seven brothers within the House of Saud -- over the country’s political landscape. Their influence had reportedly waned during Abdullah’s reign, who was not a member of this alliance.

The latest reshuffle comes amid increasing regional tensions between Sunni Saudi Arabia and Shiite Iran, following the former’s decision to carry out airstrikes on Iran-backed Houthi targets in Yemen. Bin Nayef, who is widely known as Saudi Arabia’s “counterterrorism czar,” has played a key role in the military campaign in Yemen.

The royal decree also replaces foreign minister Saud al-Faisal with Adel al-Jubeir, who is currently Saudi Arabia’s Washington ambassador and the first non-royal to hold the post.