Over the last few days, U.S. forces in Yemen have been evacuated in haste, reportedly leaving behind troves of sensitive documents.In an interview with The Daily Beast, Senator Richard Burr, the chairman of the Senate Intelligence Committee, underscored the chaotic development of events on the ground in Yemen. “We’re totally out,” he told our correspondent Tim Mak. “Yemen is going to be, in the president’s own words, a ‘model,’ [but] not of success, [instead] of absolute failure of our foreign policy.”Since late last year, Tehran’s backing for the Houthi rebels has been increasingly obvious. They took control in the capital Sanaa in January, ousting President Abed Rabbo Mansour Hadi from his palace there, and they have been closing in on his displaced government in the southern Yemen city of Aden. Hadi is now reportedly in the Saudi capital, Riyadh.From the Saudi point of view, Iran is gaining strength in Syria, where it is the embattled Assad regime’s most important ally, in Iraq, where it is propping up the mainly Shiite central government, and now in Yemen. All of these countries are on Saudi Arabia’s borders, and, what is more, to the extent that pro-Iranian Shiite forces appear to be gaining momentum, that threatens to disrupt the fragile equilibrium in the oil-producing Eastern Province of Saudi Arabia, which has a majority Shiite population. Partly because of fears the crucially important production from Saudi Arabia may be disrupted, oil prices rose dramatically on Thursday.“The Saudis are scared right now. They’re worried about Iran,” a U.S. official in contact with governments in the region told The Daily Beast. Riyadh may have notified the United States about their airstrikes, but they made it clear that they weren’t waiting for the American military to come to their aid, the official said.