Since 2000 the situation has changed completely. The most significant factor was the United States administration's decision to invade Iraq in 2003, which led to the fall of Saddam, a Ba'athist leader with pan-Arab sympathies who was determined to balance Shi'a Iran's regional influence. With the deposition of Saddam, Iran found a major obstacle to its expansion removed. This gave Iran a good chance to emerge as a major player in the Middle East.