PRIME Minister John Howard has blasted US presidential candidate Barack Obama, saying his policy of withdrawing troops from Iraq will destabilise the entire Middle East. Senator Obama, who is aiming to be the first black American president, has vowed to withdraw US forces if elected. But first, he must secure the Democratic nomination by overcoming his chief rival, Hillary Clinton. Senator Obama has introduced a bill to remove US combat forces from Iraq by March 31 next year - but the legislation has virtually no chance of becoming law while George W Bush is president, and the presidential election is...