WASHINGTON — Players on all sides of the Persian Gulf diplomatic crisis were in Washington, D.C., on Tuesday, making their cases to a divided administration that has been unable to stop the turmoil in the strategic region.Qatari Foreign Minister Mohammed bin Abdulrahman al-Thani’s meeting with Secretary of State Rex Tillerson came just days after his government dismissed a list of demands from Saudi Arabia, the United Arab Emirates, Bahrain and Egypt as an illegal attempt to limit Qatar’s sovereignty and control its foreign policy.As al-Thani and Tillerson conferred behind closed doors at the State Department, Saudi Arabian Foreign Minister Adel al-Jubeir told reporters at his country’s embassy here that the demands were nonnegotiable.“We’ve made our point.