The primary purpose of guided missile destroyers is missile defense. Modern destroyers are capable of staying on station almost indefinitely and defending them

The primary purpose of guided missile destroyers is missile defense. Modern destroyers are capable of staying on station almost indefinitely and defending themselves and allied vessels from nearly any existing airborne threat. Such a platform needs to be on station and close to assets at risk so it can interdict. You would need to orbit these platforms continuously to provide protection, and would need more than one of them at all times. Missile defense has been one of the biggest topics in international security over the last year, and is Trump's biggest defense priority. This is not a good sales pitch.