After one has served a general four year enlistment and has been discharged, is one free of all obligations to the military or may one be recalled and required to comply?
Those who are discharged before completing 8 years of active duty or reserve duty in an active drilling status are transferred to the Individual Ready Reserve (IRR) for the remainder of their military service obligations (MSO). The Individual Ready Reserve does not drill or receive pay; however, a member in IRR status can be recalled to active duty during time of war or national emergency until the 8 years have expired. Most members separating with an honorable discharge after completing a single term of service (typically 3–6 years) are transferred to the IRR for the remainder of the 8-year MSO.
https://en.wikipedia.org/wiki/Military_discharge
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