On Friday, King Salman bin Abdul-Aziz Al Saud vowed to the policies of his predecessor, the late King Abdullah bin Abdulaziz, as he took over the reign of Saudi Arabia, one of the closest Middle East allies of the United States. The new ruler called for unity among his region's countries in a period of widespread unrest.

Salman succeeds his half-brother who died early Friday at the age of 90 from complication of pneumonia.

"The Arab and the Islamic nations are in dire need of solidarity and cohesion," he said in his first speech as monarch, The Associated Press reports.

The one-time defense minister, who had increasingly taken on royal responsibilities over the past year as Abdullah became more incapacitated and said he would "continue adhering to the correct policies which Saudi Arabia has followed since its establishment."

The country is a close U.S. ally in the fight against al-Qaida and IS, the organizations responsible for, respectively, the Sept. 11, 2001, terror attacks on the United States and the establishment of a self-styled "caliphate" in Iraq and Syria known to decapitate foreign hostages and brutally repress internal opposition.

Almost immediately following Abdullah's death, the newly instated Salman, 79, also named a future successor, 69-year-old Crown Prince Muqrin. Second-in-line to the throne is 55-year-old Interior Minister Prince Mohammed bin Nayef, 55, the first grandson of Saudi Arabia's founder, King Abdulaziz Al-Saud.

Along with the royal family, Salman took part in prayers before the burial of Abdullah, according to the Washington Post. The funeral at the Imam Turki bin Abdullah Mosque in Riyadh was attended only by family members and the inner circle of aides and friends.

Present at the burial, meanwhile, were Turkish President Tayyip Erdogan and Russian Prime Minister Dmitry Medvedev, as well as the leaders of Jordan, Kuwait, Oman and Qatar. 

U.S. President Barack Obama offered his "personal condolences and the sympathies of the American people" to Saudis and the king's family, the White House said in a statement, and U.S. Vice President Joe Biden will lead a presidential delegation to Riyadh.