The band have been criticised for abandoning the true meaning of punk and selling out.
But Armstrong insists they've never lost their punk roots.
He says, "Sometimes I think we've become totally redundant because we're this big band now, we've made a lot money - we're not punk rock any more. But then I think about it and just say, 'You can take us out of out a punk rock environment, but you can't take the punk rock out of us.'
"When we started it was a proven fact that punk could not get popular. So we never played punk rock to get famous."