According to the Selective Service System, a conscientious objector is one who is opposed to serving in the armed forces and/or bearing arms on the grounds of moral or religious principles.
Conscientious objection means you simply will not and can not kill because of what you believe. To be certain that people don't claim to be CO's just to get out of being in the military, laws define a CO.
Frankly, if you don't want to kill people, the military doesn't want you. It's bad for the morale of the unit to include people who won't shoot a gun (or a missile) at human beings—and dangerous if the unit comes under fire. Peacemakers also tend to ask too many questions and refuse to unthinkingly follow orders.
However, should there be a draft, you have to prove that you are a conscientious objector as defined by United States law. How ironic—at the same age we in the church tend to think youth are entitled to be uncertain of their beliefs and direction in life, the U. S. government believes a young person is not only sure of his/her belief, but has also been living it. Can your life provide evidence of this conviction?