I did lil bita research, Seems they test you once you sign up at MEPS during your physical and such, then again at MEPS right before you ship and then AGAIN at Bootcamp, after that active duty your randomly testd on a pretty average basis, aka about a month before you go to Bootcamp you better stop puffin.
i think you could smoke pot and function in the military easily, less physically harming and draining then alcohol, i mean if you didnt abuse it of course,i mean you cant be smoken 24/7 and function, no, but im sure you could smoke on your off days and return to duty perfectly fine. OH WELL:D learn somethin new everyday!