Fugitive Taliban leader Mullah Mohammad Omar on Monday vowed more attacks against U.S. forces in Afghanistan, a day after Afghan President Hamid Karzai suggested he "get in touch" if he wanted peace. In a message to mark the three-day Muslim festival of Eid al-Adha, which starts in Afghanistan on Tuesday, Omar reiterated his call for jihad, or holy war, against the United States. "The Taliban attacks in Afghanistan will further intensify in this New Year, which will force Americans to leave Afghanistan very soon," he said in a message carried by the Pakistan-based Afghan Islamic Press (AIP) news agency.AIP said the message had been read over the telephone by a Taliban spokesman, Mohammad Hanif. Omar, whose whereabouts have been unknown since U.S.-led forces toppled his government in late 2001, said jihad was a religious obligation for Muslims as the United States was "the biggest enemy of Islam." "Muslims should stand prepared for the sacrifice of jihad on the great day of Eid al-Adha because armed jihad is the only way to safeguard the Islamic world."