If you recall during the first Gulf war … Kuwait re-flaged their tankers to US flag. This entitled them USN escort through the Arabian Gulf. Each tanker had an American Master (paper). RE-flaging also allows you to get preference over foreign flaged ships when bidding US GOV. cargoes going foreign or returning from overseas. The only time this would make sense for Jones Act trade was if there wasn’t a suitable Jones Act vessel available. Then it takes an act of Congress to deliver a waiver.