Apple CEO Tim Cook warns Washington against “Big Tech” antitrust regulations that sacrifice privacy and security on iPhones.

Cook used his keynote address at the International Association of Privacy Professionals Global Privacy Summit to address the harmful implications of the Open App Markets Act, legislation sponsored by Connecticut Sen. Richard Blumenthal, Tennessee Sen. Marsha Blackburn, and Minnesota Sen. Amy Klobuchar, which would regulate how companies operate online marketplaces for digital applications like Apple’s App Store.