UFC star Dominick Cruz had to go radio silent recently during a secret trip to various U.S. military bases across the globe -- where he got to train soldiers how to punch and kick like an MMA fighter.

It's a great story -- and Cruz was clearly honored to work with the USO.

Cruz joined the guys on the "TMZ Sports" TV show (airs Friday night on FS1) to talk about it and explained what it was like to trade shots with one of the most powerful military leaders on the planet.

Props to Cruz. Props to our soldiers. Stay safe out there.