Saudi Arabia's King Salman has issued a series of royal decrees bringing about a dramatic reshuffling in the line of succession and ushering in a younger generation to take up key ministerial positions.

This is the second major shake-up to the ranks of power in the kingdom since the 79-year-old Salman assumed the throne Jan. 23.

(There are roughly 15,000 princes and princesses in Saudi Arabia, but power is consolidated among a few. You can follow along with this helpful Wall Street Journal family tree.)

The most surprising change is the naming of a new heir to the throne. Crown Prince Muqrin bin Abdulaziz is out, replaced by the country's powerful interior minister, Prince Mohammed bin Nayef, who also happens to be the king's nephew. Prince Muqrin was close to King Abdullah, who died in January.

Replacing him with Prince Nayef as crown heir is the equivalent "of defenestrating Prince Charles and installing Prince William as the Prince of Wales," according to The Guardian.

In another move, the king's son Prince Mohammed bin Salman is now second in line to the throne. Prince Mohammed, who is believed to be about 29, is also Saudi Arabia's defense minister.

Prince Nayef and Prince Mohammed are grandsons of the kingdom's founding monarch, Abdulaziz Ibn Saud. NPR's Leila Fadel says the royal decrees push a new generation into the line of succession.

Both men are seen as ensuring Saudi Arabia will have a more aggressive foreign policy, one that was heralded when King Salman took power. This includes confronting its regional rival, Iran.

The kingdom has also taken on a more active military role, joining a U.S.-led push against militants with the self-proclaimed Islamic State. Prince Mohammed also has spearheaded a controversial Saudi-led air campaign against Houthi rebels in neighboring Yemen.

Iran's supreme leader, Ali Khamenei, has criticized Saudi's actions in Yemen, according to The Wall Street Journal, saying the kingdom's traditional caution in world affairs has been jettisoned by "inexperienced youngsters who want to show savagery instead of patience and self-restraint."

In another surprising move, the king is replacing the veteran foreign minister, Prince Saud al-Faisal. Riyadh's ambassador to the U.S., Adel al-Jubeir, 53, will take up the post that Prince Saud, 75, has held since 1975.

Jubeir is not a member of the royal family, but King Salman is seen as entrusting the job of foreign minister to someone who knows Washington well and can communicate with the Obama administration, according to Gulf News.

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