By Parisa Hafezi, Samia Nakhoul and Jonathan Saul DUBAI, July 16 (Reuters) - Iran has asked Yemen’s Houthi movement to stand ready to close the Red Sea oil route if the United States strikes Iranian power infrastructure, three sources told Reuters on Thursday, posing a potent new threat to global energy supplies. The idea has been discussed within the Islamic Republic's leadership, and the message has been conveyed to Iran's Houthi allies, two senior Iranian sources and a regional source familiar with the matter said, speaking on condition of anonymity.