US President Barack Obama (C-L) is greeted by Saudi Crown Prince Salman bin Abdulaziz al-Saud (C-R) upon his arrival at Rawdat Khurayim, the monarch’s desert camp 60 miles (35 miles) northeast of Riyadh ahead of a meeting with Saudi King Abdullah, on March 28, 2014. Obama arrived in Riyadh for talks with Saudi King Abdullah as mistrust fuelled by differences over Iran and Syria overshadows a decades-long alliance between their countries. AFP PHOTO / SAUL LOEB