Walter's theory is that the hijacked planes were replaced by remote controlled drones that were crashed into the World Trade Center and Pentagon, while the buildings were brought down by preset explosives, to create a pretext for the war in Afghanistan and 2003 invasion of Iraq. At the web site, Walter offered a US$10,000 reward for a mathematical proof of how the World Trade Center buildings collapsed from the fire and impact, the way the 9/11 Commission said. By 2005, the reward had grown to $1,000,000 for proof that explosives were not used in the collapse of the World Trade Center.