>Not their job.
Wrong, every service-member takes an oath to the CONSTITUTION, which is what gives the President authority over the armed forces. If a person is not qualified to hold the office of President, how can the President be named the Commander-in-Chief?
Read this analysis of the oath that Army enlisted take:
http://docs.google.com/View?id=dv698tm_25c7b35cc9
this is the oath I took -
Oath for Commissioned Officer
“I HAVING BEEN APPOINTED AN OFFICER IN THE ARMY OF THE UNITED STATES, AS INDICATED IN THE ABOVE DO SOLEMNLY SWEAR (OR AFFIRM) THAT I WILL SUPPORT AND DEFEND THE CONSTITUTION OF THE UNITED STATES AGAINST ALL ENEMIES, FOREIGN AND DOMESTIC; THAT I WILL BEAR TRUE FAITH AND ALLEGIANCE TO THE SAME; THAT I TAKE THIS OBLIGATION FREELY, WITHOUT ANY MENTAL RESERVATION OR PURPOSE OF EVASION; AND THAT I WILL WELL AND FAITHFULLY DISCHARGE THE DUTIES OF THE OFFICE UPON WHICH I AM ABOUT TO ENTER. SO HELP ME GOD”
Who Enforces the Constitution's Natural Born Citizen Clause?