Crown Prince Mohammed bin Salman of Saudi Arabia had a detailed discussion about the war in Yemen on Tuesday in a meeting with US President Joe Biden's national security adviser, Jake Sullivan, a senior administration official said. The war, in which a Saudi-led coalition is battling the Iran-backed Houthi rebels, has devastated Yemen's economy and depleted foreign exchange reserves in the impoverished Arabian Peninsula nation. Mr Sullivan is on a<a href="https://www.thenationalnews.com/gulf-news/saudi-arabia/2021/09/27/us-national-security-adviser-heads-to-saudi-arabia/#:~:text=US%20National%20Security%20Adviser%20Jake,NSC%20spokesperson%20Emily%20Horne%20said." target="_blank"> trip this week to Saudi Arabia and the United Arab Emirates</a>, accompanied by the US special envoy to Yemen, Tim Lenderking and Biden Middle East envoy Brett McGurk. As well as the crown prince, Mr Sullivan met Deputy Defence Minister Prince Khalid bin Salman, Interior Minister Abdulaziz bin Saud bin Nayef and National Guard Minister Prince Abdullah bin Bandar, among others. “They had a detailed discussion of the Yemen conflict and both parties endorsed the efforts of the new UN special envoy to Yemen Hans Grundberg and agreed to intensify diplomatic engagement with all relevant parties. Special Envoy Lenderking will remain in the region to follow up on the detailed discussions,” the official said. The United Nations has described the situation in war-torn Yemen as the world's largest humanitarian crisis. Seven years of fighting have plunged the nation into an economic crisis, triggering food shortages. Yemen imports most of its supplies. The official said Mr Sullivan thanked the crown prince for “Saudi Arabia’s hospitality in permitting thousands of at-risk Afghans to transit through Saudi territory” during Mr Biden's withdrawal from Afghanistan last month.