(Adds General Casey's comments) BAGHDAD, Oct 24 (Reuters) - The U.S. ambassador to Iraq urged Iraqi leaders on Tuesday to work harder to achieve key political and security goals. Zalmay Khalilzad said that success in Iraq was still possible and could be achieved in a "realistic timetable". Khalilzad was speaking at a news conference with the top U.S. commander in Iraq, General George Casey. Casey accused Iran and Syria of providing support to armed groups in Iraq, a move he described as "decidely unhelpful".
