President Joe Biden will announce an end Thursday to U.S. support for a grinding five-year Saudi-led military offensive in Yemen that has deepened human suffering in the Arabian peninsula’s poorest country, national security adviser Jake Sullivan said. Biden sees the United States “playing a more active and engaged role” to end the war through diplomacy, Sullivan said at a White House briefing before Biden was set to speak at the State Department. Thursday’s move, which fulfills a campaign pledge, would not affect any U.S. operations against the Yemen-based al Qaida in the Arabian Peninsula, or AQAP, group, Sullivan said. Yemen, the biblical kingdom of Sheba, has one of the world’s oldest constantly occupied cities—the more than 2,000-year-old Sanaa—along with mud brick skyscrapers and hauntingly beautiful landscapes of steep, arid mountains. But decades of Yemeni misgovernment have worsened factional divisions and halted development, and years of conflict have now drawn in …