But if Mr. Hussein is executed for the Dujail killings , he will never be called to account for the larger atrocities on which he was arraigned in July 2004 : killing political rivals , crushing the Shiite uprising in southern Iraq in 1991 , invading Kuwait in 1990 , and waging the genocidal Anfal campaign against the Kurds in 1988 , including gassing Kurdish villagers at Halabja .