Two very bright square flashing lightsAs my wife and I were sitting on our back deck looking towards the SW we both saw two bright square flashing lights. It was as if they were LED lights. They blinked with no other lights. We also heard what sounded like jet engines, but the sound was behind the flashing lights by about two seconds. The sound was quiet not the usual jet engines you normally hear. We are right in the flight path of Sea Tac and McCord so we see a lot of plane traffic. I have been an airplane watcher for over 35 years and have never seen anything like this. We watched it fly from the SW to the North. Again very strange square lights!