I think it was Napoleon who said that the inevitable result of a defensive war is surrender. George W. Bush was on the offensive in the War on Terror in Iraq and Afghanistan and we were winning big time. People who argue a defensive posture just don't get it.
After 8-years of a defensive (at best) posture by President Obama ISIS is now bigger than al Qaeda ever was according to Obama's own CIA Director John Brennan.
History won't be kind.