The foreign affairs adviser to Pakistan's prime minister said Thursday that "all indicators" confirmed that the former Taliban chief Mullah Akhtar Mansour was killed in a US drone strike in the country's southwestern Baluchistan province, where he was traveling under a false name with fake Pakistani identity documents. At a news conference in the capital, Islamabad, Sartaj Aziz said authorities were awaiting DNA test results, after which Mansour's body will be handed to his relatives. Aziz's comments came a day after the Taliban announced that the group's council of leaders had unanimously selected Mullah Haibatullah Akhundzada as its new head following the death of Mansour. During an official visit to Japan on Thursday, US President Barack Obama said that he was not optimistic about a change for the better any time soon after the killing of Mansour. Mansour had entered Pakistan from Iran under a false name, with a Pakistani ID card and passport, Aziz said. He refused to elaborate, saying that Pakistani authorities were still investigating the reason for Mansour's trip to Iran. Pakistani authorities have detained two officials from southwestern Baluchistan who helped Mansour obtain his Pakistani national identity card, the interior ministry said. Aziz condemned the US drone strike, saying it was a "violation of Pakistan's sovereignty" and said Pakistan had "conveyed our serious concern to the United States on this issue." The drone attack had "undermined the Afghan peace process," Aziz said, but he added that he still believed that the way to resolve the Afghanistan's conflict is through negotiation. "In our view there is no military solution to the conflict in Afghanistan. The use of force for past 15 years has failed to deliver peace," he said. Pakistani authorities have long been accused by both Kabul and Washington of giving shelter and support to some Taliban leaders — an accusation that Islamabad denies. The insurgents have been fighting to overthrow the Kabul government since 2001, when their own Islamic regime was removed by the US invasion.