>While I can't picture myself taking up (cyber) arms against a foreign nation, aren't EU / US law quite explicit about the legality of meddling as a civilian?

>While I can't picture myself taking up (cyber) arms against a foreign nation, aren't EU / US law quite explicit about the legality of meddling as a civilian? To actually take a shot at your question, for the US at least in general it appears to be perfectly legal purely as a matter of current US law for a private citizen to go and fight for another country, so long as it's not against the US. I could have sworn this had come up fairly recently in the midst of all the middle east battles and indeed Foreign Policy had a whole article devoted to it in 2011: "Is It Legal for Americans to Fight in Another Country’s Army?" [0]. Caveats don't seem to apply here, obviously the UA is not an American "designated terrorist organization", Russia is not an ally (to put it mildly), etc. So just in terms of "could an American go volunteer for this?" answer seems to be yes. Of course in practice it's a lot more complicated. Being legal to go fight in another army has nothing to do with actually getting there, what you can bring, and coverage for your actions. Unless you have a direct private US<>Ukraine flight or boat, have to check on transit laws for all the countries one is going through. Laws about transport of weapons or equipment (ITAR) still apply, though things you bring purely for your own use may be allowed but it's not clear at a glance. Bringing extras would definitely require licensing. Regulations for commercial air/sea travel, customs and so on still apply. If an officially sanctioned uniformed part of the UA volunteers should be protected by the GC and POW treaties and so on same as any other soldier, but of course Russia's adherence to that isn't a given, and they won't actually have the US military backing them directly like a US soldier would. Any crimes committed could be prosecuted, and there are requirements for GC coverage (like being in uniform, chain of command) that over enthusiastic volunteers might ignore at their peril. Russia could well be expected to flat out invent supposed crimes they "saw" volunteers committing and that wouldn't be trivial to avoid if captured. And much more. It's a heroic cause and if somebody or some group was serious about navigating all that and accepting the risk even beyond that to their lives I'd honor them for it, and if all went well and they made it home there doesn't appear to be any legal risk back here so there is that. But it'd be an even more serious business than going to fight as part of the regular US forces. ---- 0: https://foreignpolicy.com/2011/09/02/is-it-legal-for-americans-to-fight-in-another-countrys-army/ https://foreignpolicy.com/2011/09/02/is-it-legal-for-america...