A senior United States military commander in Iraq has said that most of the leaders of the Al Qaeda organisation there have been captured or killed over the past three months. Gen. Ray Odierno told a news conference at the Pentagon that of the 42 top leaders, only eight remained free. <br/> <br/>But, he cautioned against complacency, saying that, even with the setbacks, al-Qaeda was trying to regroup and would remain a problem for years. He added that the number of attacks and casualty figures suffered by US troops had fallen to their lowest level since the US-led invasion of the country in 2003. <br/>