Photo Essay - 91st SFG holds Global Strike Challenge tryouts Published Sept. 21, 2011 Minot Air Force Base Public Affairs MINOT AIR FORCE BASE, N.D. -- The 91st Security Forces Group held tryouts Sept. 21 here for a chance to represent their wing in the second annual Global Strike Challenge.The GSC is a competition where Air Force Intercontinental Ballistic Missile and bomber forces compete against one another to be recognized as the best at what they do in the command. The challenge will be held at Barksdale AFB, La. To view a slideshow of Airmen competing at the tryouts click here.