USERRA covers military duty. Does not have to be "recalled" or "activated", just has to be duty, which (almost all) active duty qualifies.

Your job rights are guaranteed for 5 years (per employer) but there are exceptions. For example, service commitments beyond the 5 years would extend USERRA protection.

So if you went to a formal training school at year 4 while on active duty, and it incurred an additional 3 year commitment, then you would be protected for the full 7 years.