Last edited by emileverbunt; 10-29-2010 at 10:16 AM. Reason: adding link
here is a unusual photo I found showing a Cambodian soldier in 1970 eating from a rice bowl and wearing the same model helmet as yours, the newspaper photos describes it as a Russian helmet, but they are incorrect, it's actually a French M51 and it looks like the soldier used some material to make a replacement field repair chin strap
This helmet is a French army helmet mod. 1951.
I have this one on my head when I was first lieutenant in the french army 1974 - 1976.