US-Britain Al-Qaeda leader Osama bin Laden's right-hand man Ayman al-Zawahiri warned Britain and the United States of more horror and destruction in a new videotape shown on Al-Jazeera television. Iraq Iraqi leaders prepared for a conference to try to break the deadlock on a draft constitution amid unabated violence that left at least 20 people dead, a day after 15 US marines were killed by rebels. Britain Thousands of police mounted a huge operation to protect London, exactly four weeks after suicide bombers brought carnage to the city, while a suspect in a bungled second wave of attacks appeared in court. NKorea Talks on North Korean nuclear disarmament were deadlocked when the Stalinist state refused to give up nuclear programs for peaceful purposes -- the key stumbling block in negotiations. US NASA considered ordering an unscheduled spacewalk to repair a thermal blanket on Discovery, as the crew moved supplies into the International Space Station which faces a long wait for another lifeline-visit from a US shuttle. Canada The Air France jet which crashed at a Toronto airport was working normally as it arrived, Canadian investigators said amid a dispute over who said it could land in a storm.