US President George W. Bush has told Americans that the o­nly way to limit the length and scope of combat in Iraq was to use decisive force.

After US and British aircraft unleashed the devastating firepower of missiles and bombs the Pentagon calls "shock and awe," Bush warned the Iraqi government, "This will not be a campaign of half measures."

Reuters reported that three days into war, Bush also cautioned against overconfidence given the apparent success of the mission and lack of serious resistance so far.