How do you manage friendships with foreign military service members?

I don't manage them, I cherish them as I do any others. They were formed in many of the same ways I formed friendships with my American neighbors. Facebook has certainly opened the "floodgates" to the world, as has the Internet, at large. I love what it has done to increase my circle of friends around the globe.

I do, 2 from the UK, 1 from Iraq, 1 from France.
Some are just acquaintances that say hi once and awhile, 1 is a closer friend and if we lived on the same side of the earth would hang out often I think.

For a security clearance, you will need to report any relationships with non-US citizens that is outside of a military relationship or a one-time meeting. So if they are a friend that you converse with in any form or a business partner, you must report it. I think this would include a member of a foreign military that you maybe met first on a mil to mil engagement but it proceeded well beyond that. So if you consider them a friend, report it. I would also say that you should know at least a little of their background so you are not associating with someone who has views, connections, etc. of something that may get you in trouble. Also, their country of origin will also be an issue and you can probably figure out which countries of origin will be more questionable. But as long as you are forthright when going for a clearance, it should not be a problem.