"The more that time goes by, the more doubt is raised about the actions taken by Saudi Arabia and the UAE", Nauert said. Currently, there are more than 15,000 descendants of the royal family. Pledging allegiance to the new crown prince has been one of the high trending hashtags on social media since the news was announced.
Although Mohammed bin Salman's promotion to crown prince had always been expected among those who follow the royal family closely, the timing was a surprise, and puts the kingdom's future in relatively untested hands.
Mohammed bin Salman chipped away at his authority but Mohammed bin Nayef's popularity with the previous US administration of Barack Obama had prevented his ouster, said Stephane Lacroix, associate professor at Sciences Po university in Paris. "I am content", Prince Mohammed bin Nayef said.
The 31-year-old replaced his cousin Mohammed bin Nayef as next in line to the throne after a royal decree was issued by his father, King Salman, on Tuesday.
Analysts said the change ends uncertainty over succession and empowers Prince Mohammed bin Salman to move faster with his plan to reduce the kingdom's dependence on oil, which includes the partial privatisation of state oil company Aramco.
Sheikh Tamim bin Hamad Al Thani sent a cable of congratulations to the new crown prince of Saudi Arabia yesterday, even though many consider him to be an architect of the Gulf dispute. British Prime Minister Theresa May also welcomed Prince Mohammed's appointment.
Mohammed bin Nayef became crown prince in 2015 after the death of the previous king, Abdullah bin Abdulaziz.
Saudi Arabia has always been ruled by septuagenarian or octogenarian kings.
The power shift may be significant, but it could also just be cosmetic.
Although he is still in his youth, Mohammed bin Salman has for a long time held senior government positions and has been at the forefront of the kingdom's plans to wean itself off oil as one of economic strategies that were launched a year ago.
In a royal decree early Wednesday, Salman placed his son, Mohammed, 31, as first in line to the throne. "But if these changes do not take into account the specifics of the region, this may lead to more serious crisis in the future", he said.
"We look forward to continuing our work with Crown Prince Mohammed bin Salman in his new role to defeat terrorism and improve our mutual security, stability, and prosperity", State Department spokeswoman Heather Nauert said in a statement Wednesday.
Iran, which is predominantly Shi'ite Muslim, and Saudi Arabia, which is mostly Sunni, compete for power and influence across the region.