White House national security adviser Jake Sullivan spoke by phone with Saudi Arabian Crown Prince Mohammed bin Salman on Tuesday amid signs that the Saudis and Iran-allied Houthis in Yemen are making “significant progress” toward finding a permanent end to their nine-year conflict. The call was revealed to The Associated Press by a senior administration official who spoke on condition of anonymity. The crown prince has had a strained relationship with President Joe Biden over human rights and oil production concerns. The call came after a Saudi diplomat met with Houthi officials in Sanaa on Sunday for talks that were aimed at accelerating negotiations to end the war.