Apple CEO Tim Cook said that feedback about Apple Pay has been “overwhelmingly positive and enthusiastic”, as he announced at The Wall Street Journal‘s Digital Live conference that, in the first 72 hours of the service being launched, 1 million credit cards in the US were activated to be used with it.

This figure includes only iPhone 6 and iPhone 6 Plus users, as the service is only available on the new devices. Apple Pay launched on 20 October.

“The early ramp [of Apple Pay] looks fantastic,” said Cook (pictured), adding that retailers who do not yet offer the service may have to do so if that’s what their customers want.

He cited security as one of the reasons for its successful takeup, as it eliminates chances of card details being stolen, and clarified that no data is stored by Apple.

Cook also said a potential partnership with China’s Alipay, an online payment system third only to MasterCard and Visa, was on the agenda but no specifics were mentioned.

Cook also reiterated that the majority of Apple’s revenue will continue to come from the iPhone.