ISTANBUL — Saudi Arabia appointed a princess as its new ambassador to the United States on Saturday, the first time the kingdom has named a woman to such a post.

The appointment of Princess Reema bint Bandar bin Sultan by royal decree came amid strained relations between Saudi Arabia and the United States over the killing of the Saudi dissident Jamal Khashoggi by Saudi agents in Istanbul in October.

While members of Congress have pursued measures to hold Crown Prince Mohammed bin Salman responsible for the killing and to cut military aid to the Saudi war in Yemen, President Trump has stood by the kingdom, seeing it as a valuable Middle Eastern ally and reliable buyer of American weapons.

Princess Reema will replace Prince Khalid bin Salman, a son of King Salman and a younger brother of the crown prince, who took the post in 2017. Also in a royal decree on Saturday, Prince Khalid was named deputy defense minister under the crown prince, who heads the ministry.