Nearly 5 years after the United States invaded Iraq, the tremors from this cataclysmic event are still reverberating in the region and around the world.A new generation of jihadist extremists is gaining experience on the battlefields of Iraq, and what passes for political authority seems increasingly wielded by nonstate groups via the point of a gun.All the surrounding states view developments in Iraq with varying levels of disquiet.Many commentators believe that the invasion has become the most important regional event framing political and military affairs since the 1967 Six-Day War.The war has dramatically altered internal political dynamics throughout the region, placing the regimes and their historically close relations with the United States under new pressures.All these forces are converging to frame a new strategic challenge to the United States and the international community, which has vital economic and political interests in ensuring regional stability and security.