and includes service as a cadet at the United States Military Academy, the United States Air Force Academy, or the United States Coast Guard Academy, or as a midshipman at the United States Naval Academy, but does not include service in the National Guard except when ordered to active duty in the service of the United States or full-time National Guard duty (as such term is defined in section 
101
(d) of title 
10) if such service interrupts creditable civilian service under this subchapter and is followed by reemployment in accordance with chapter 
43 of title 
38 that occurs on or after August 1, 1990;