"The HTTP 418 I'm a teapot client error response code indicates that the server refuses to brew coffee because it is, permanently, a teapot. ... This error is a reference to Hyper Text Coffee Pot Control Protocol defined in April Fools' jokes in 1998 and 2014."
I suspect that it is a common practice for military sites to block foreign IPs. When I google "Join the army," I cannot find any recruitment pages for any non-US armies. Even when I explicitly google something like "Join Mexican army," I see nothing. Seems like this is a behavior that was deliberately designed.
Have you tried searching using the language spoken in the country instead?