Saudi Arabia’s King Salman has been meeting US President Barack Obama in Washington, with Iran and Yemen topping the agenda.
It is the king’s first visit to America since ascending to the throne in January and comes after a nuclear deal was agreed with Tehran.
There are Gulf Arab fears that a lifting of sanctions will enable the Islamic Republic to pursue destabilising policies in the Middle East.
As the two met, protesters gathered outside the White House to voice their views over the turmoil in Yemen.
There have been tensions between the US and Saudi Arabia over what Riyadh sees as a lack of direct US action against President Bashar al-Assad in Syria.
A perceived American tilt towards Iran since the Arab Spring uprisings has also been straining relations.