There isn’t an embargo as such. …..As Legends proves every year ….but:
Any former military aeroplane is subject to investigation as a potential ‘weapon of war’, involving all sorts of agencies from the FAA, to Homeland Security and Department of Defense.
If its over 60 years old, it also becomes at ‘potential national treasure’ and it’s leaving the USA may have to be approved by their heritage authorities.
It shows the worth of having a good, on the ball, shipping agent!!