IF this was a missle, then
there just might—MIGHT—be a connection between the world economic meeting in Seoul, and the news today that North Korea has or is working on a sub-launched ICBM (perhaps just a simple arrangement in which an ordinary sub tows a launch pad behind it; it may even surface to launch).
The “missle launch” has been basically proven to be a jet.
1 the contrail did not disperse as a rocket would have
2 the flame from a rocket motor would have been much brighter.
3 any large missle shows up big time on radar.
4 only the usa has ever bult a curise missile with stealth. Rockets with current material science can’t be stealthy.
5 an aviation enthusiast has already figure out the plane.