Despite nuclear tensions, a group of American runners traveled to North Korea this past weekend to compete in the Pyongyang marathon ... and TMZ Sports has the incredible footage.
It all went down on Saturday -- when 1,000 foreign runners from all over the world gathered in front of roughly 70,000 people at Rungrado 1st of May Stadium ... the largest stadium in the world.
One of those people was Brian Sloan -- an American entrepreneur who created the Autoblow sex toy (don't pretend like you don't know what it is).
Sloan says entry into NK was as complicated as you'd expect -- with military people thoroughly inspecting his belongings .