 The most serious fighting breaks out as the Hezb-i-Islami, led by firebrand fundamentalist Hekmatyar, rains thousands of rockets on Kabul from hilltop positions on the southeastern outskirts, bringing more destruction than has taken place in the 14-year war between Soviet-backed Communist regimes and the Muslim resistance.The government also faces a serious challenge from an Iranian-backed alliance of Shi`ite Muslims.The Unity Party, a coalition of eight Shi`ite Muslim parties that enjoys the moral and financial backing of Iran, demands that the interim government honour past promises to share power.