Australia was a divided nation last night as its troops prepared to join a United States-led invasion of Iraq and Federal Parliament descended into a bitter debate over waging war without specific United Nations backing. The Prime Minister came under heavy flak for committing the country to war after the US President, George Bush, gave Saddam Hussein and his sons until tomorrow to leave Iraq or face attack. John Howard said the coalition of US, British and Australian troops did not need further UN approval to launch the invasion. "The Government strongly believes that the decision it's taken is right,...