Burhanuddin Rabbani, who had been trying to broker a peace deal with the Taliban, was reportedly assassinated in Kabul Tuesday.
Afghan officials told The New York Times that Rabbani was likely killed by a suicide bomber in or near his home, which is near the U.S. Embassy in Kabul.
Rabbani, president of Afghanistan from 1992 to 1996, was about 80, the Washington Post reports.
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Rabbani was forced to leave Kabul after the Taliban took of the country and became one of the leaders of the Northern Alliance, which brought together warlords and political leaders to fight against the Taliban.
He went on to become the leader of Afghanistan’s High Peace Council and was responsible for bringing a political end to the war with the Taliban.
"The assassination of the influential political leader is a blow to the Afghan government's embattled effort to bring insurgents into the political fold. The United States and other Western leaders have backed the so-far fruitless effort, seeing it as the best opportunity to bring the war to an end after a decade of fighting," the Washington Post states.
President Hamid Karzai has been on a visit to New York to attend the United Nations General Assembly meeting and was planning on talking to President Obama about the 10-year war in Afghanistan, the Times reports. As a result of the assassination, Karzai will end his trip early and return home, an Afghan government spokesman reportedly said.
The killing of Rabbani lessens the likelihood that the war will be ended through a negotiated settlement, and the attack is likely to "tip the country further into political crisis," the Guardian reports.