If you actually listen to the interview, it's very clear that Trump was unsure about supporting the war. He probably always had doubts about it but reluctantly went along with it in public for a time. And, again, he was one of the first public figures to come out against the war. Even FactCheck.org admits that Trump turned against the war pretty quickly:
Trump expressed concerns about the cost of the war soon after it started.
If Trump did support the war, he turned on it quickly. As the timeline below shows, Trump in July said that he wished the money being spent in Iraq could be spent in New York City. By November, he talked about the “tremendous cost” of the war and the “very, very unpleasant surprises in Iraq.”
By 2004, Trump’s
opposition to the war was well documented. (
Donald Trump and the Iraq War )