U.S. President Donald Trump (C) and First Lady Melania Trump (L) attend a dinner given in honour of Trump by Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) at Murabba Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) welcomes U.S. President Donald Trump (C) and First Lady Melania Trump (L) ahead of a dinner given in honour of him at Murabba Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud (L) welcomes U.S. President Donald Trump (R) ahead of a dinner given in honour of him at Murabba Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud (2nd L) and U.S. President Donald Trump (2nd R) join dancers with swords at Murabba Palace ahead a dinner given in honour of Trump in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud (2nd L) and U.S. President Donald Trump (2nd R) join dancers with swords at Murabba Palace ahead a dinner given in honour of Trump in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud and U.S. President Donald Trump (not seen) join dancers with swords at Murabba Palace ahead a dinner given in honour of Trump in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) welcomes U.S. President Donald Trump (C) and First Lady Melania Trump (L) ahead of a dinner given in honour of him at Murabba Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) welcomes U.S. President Donald Trump (C) ahead of a dinner given in honour of him at Murabba Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

U.S. President Donald Trump joins dancers with swords at Murabba Palace ahead a dinner given in honour of him by Saudi Arabia's King Salman bin Abdulaziz Al Saud (not seen) in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

U.S. President Donald Trump arrives at Murabba Palace for a dinner given in honour of him by Saudi Arabia's King Salman bin Abdulaziz Al Saud (not seen) in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

Saudi Arabia's King Salman bin Abdulaziz Al Saud (C-R) welcomes U.S. President Donald Trump (C-L) and First Lady Melania Trump (L) ahead of a dinner given in honour of him at Murabba Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

U.S. President Donald Trump (L) and Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) sign bilateral agreements between two countries at Al-Yamamah Palace in Riyadh, Saudi Arabia on May 20, 2017.( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

U.S. President Donald Trump (L) meets Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) at Al-Yamamah Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

U.S. President Donald Trump (L) meets Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) at Al-Yamamah Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )

U.S. President Donald Trump (L) meets Saudi Arabia's King Salman bin Abdulaziz Al Saud (R) at Al-Yamamah Palace in Riyadh, Saudi Arabia on May 20, 2017. ( Bandar Algaloud / Saudi Royal Council / Handout - Anadolu Agency )