(CBS) An Iraqi connection with the Sept. 11 attacks is far from proven, but U.S. officials say they are following several tantalizing leads, reports CBS News National Security Correspondent David Martin. When hijacker Khalid al Midhar arrived in Malaysia in January of 2000 for a meeting of key al Qaeda operatives, he was met at the airport by an Iraqi named Ahmad Shakir, who worked part-time greeting VIPs, a job he got with the help of someone in the Iraqi Embassy. One week later, al Midhar flew to the United States, and 18 months later he was aboard the airliner...