Probably not an issue, assuming it was nothing really heavy. Had a good buddy who did a recruiter tour. They could work with juvie shoplifting, simple assault, vanadlism, *maybe* drug possession, etc. Could not work with weapons charges, sexual stuff, drug dealing, weird stuff, etc.

Also I've heard online crime, hacking, of any sort is no-go these days (security clearance disqual).

But sealed, expunged, juvenile, charges dismissed is NOT exempt from DoD (or other government agency) scrutiny. Everybody who joins in any capacity today must be eligible for a security clearance, and they need to know your history including any arrests and juvie stuff. Just because the state sealed it will not keep you out of federal prison if you get caught lying about it.