8 Year Military Commitment?

I Understand When You Enlist Active in The Untied States Army No Matter Your Enlistment Time (Example 5 Years) You Will Regardless Have Signed Up for an 8 Year Service, After Your Active Service is Finished in Your in The "Inactive Reserve Stage" of Your Time in The Military Can You Then Go On To Become a Police Officer After Your Active Service or Must it Be When Your Full 8 Year Service Time is Up ?