The United Nations joined Afghan President Hamid Karzai on Thursday in calling on the U.S. military to punish those who burned copies of the Qur\'an at a NATO air base. \"After the first step of a profound apology, there must be a second step ... of disciplinary action,\" Jan Kubis, the special representative for the U.N. secretary-general in Afghanistan, told reporters in Kabul. He called the incident a \"very unfortunate mistake ... very sad.\"