Without the 71-year-old Mr. Rabbani, it will be exceedingly difficult to move the peace process forward. A complex figure, he was nonetheless one of the few with the stature to persuade the Taliban’s enemies, the former Northern Alliance, to embark on reconciliation discussions.

Western diplomats said that recently Mr. Rabbani had begun discussions with some Taliban members who might have the power to engage in real negotiations. A number of previous contacts had proved to be with impostors or figures who had little authority…

Within hours of the killing, Northern Alliance leaders, most of whom are ethnic Tajiks and Hazaras, as well as some prominent Pashtun figures, were on television, denouncing the peace process and saying that the Taliban could not be trusted. The Taliban are predominantly ethnic Pashtuns…

Dr. Abdullah added: “We have to be realistic about what we are up against. We are up against people who don’t believe in any humanity. They assassinate people on the streets of Kabul, they assassinate those trying to achieve peace.”