The United States has asked Pakistan to arrest and bring to justice a Taliban militant commander to underline its commitment to the “war on terror.” The commander, Baitullah Mehsud, who has been accused by the CIA of masterminding the assassination in December of ex-premier Benazir Bhutto, has been negotiating with the new Pakistan coalition Government.The Government, led by Prime Minister Yousuf Raza Gilani, has pledged to completely overhaul Islamabad's counter terrorism pursuit after defeating US-backed President Pervez Musharraf’s political allies in February elections.US Deputy Secretary of State John Negroponte told a Congressional hearing on Tuesday that Washington was concerned over the negotiations with the Taliban, whom US and NATO troops are fighting in neighbouring Afghanistan. He said Washington had repeatedly cautioned Islamabad about the talks despite a pledge from Gilani’s Government not to give “free space” to the extremist group using remote tribal areas as safe haven to attack Afghanistan.