Military service is mandatory in the United States O when a man has been selected from the draft.
O only in times of war.
O for unemployed citizens.
O when national defense is at great risk.

when a man has been selected from the draft

Explanation:

Someone is only mandated to serve in the military if they were drafted.  

hola,

i hate my life too. (like jayfeather hates his blindness x3)

the monroe doctrine is the best known u.s. policy toward the western hemisphere. buried in a routine annual message delivered to congress by president james monroe in december 1823, the doctrine warns european nations that the united states would not tolerate further colonization or puppet monarchs.