WASHINGTON The head of the UN Assistance Mission for Iraq (UNAMI) delivered his final briefing to the Security Council on Tuesday, marking the approaching end of the mission’s 22-year mandate on Dec. 31 and reflecting on what he called “hard-won gains” for Iraq. Mohamed Al Hassan opened the session by thanking Council members for their “invaluable support and guidance” and expressed profound gratitude to the government of Iraq for hosting the mission since its establishment in 2003. He also