This is from the documentary
Trinity and Beyond: The Atomic Bomb Movie. The footage is from the first ChiCom nuclear test in 1964: among other things, it has horse cavalry charging the GZ after the detonation..complete with drawn sabers. Note that the horses have masks and NBC suits as well for the most part. Only in Maoist China would you have something like this....though if the NKs were stupid enough to set off atmospheric tests, they might do the same thing!
http://www.youtube.com/watch?v=9rd9ylueyBY
(Uploaded by someone in China)
http://www.youtube.com/watch?v=luZtl2J3sR0
(this version is a cleaner one of the first)