U.S. Defence Secretary Pete Hegseth says much of Iran's aerial defences have been destroyed, enabling an expansion of U.S. bombing in the coming days.

But in modern history, a military operation has never managed to change a regime from aerial bombing alone.

That's according to Robert Pape - who has studied every air campaign since World War I and warns the U.S. strategy of "strategic bombing" against Iran could backfire - escalating the conflict without delivering regime change.

• GUEST: Robert Pape, Professor of Political Science at the University of Chicago 
• PRODUCER: Pip Cook & Eddy Diamond