In 1995, Shawn Nelson, a former Army tank commander drove into a National Guard armory and stole an M60A3 tank. He drove the tank out of the armory, and onto residential streets where he began crushing things in his path. He drove the tank onto a highway and was pursued by a number of San Diego Police Department cars.
Eventually, Nelson crashed the tank into a concrete barrier and police embarked on top of the turret where they cut the hatch open with bolt cutters. Nelson began to spin the tank in an attempt to shake the officers off and was shot by police.
Yeah, to secure a military vehicle in a lot, they use a regular padlock. Guarantee a key is lost every quarter, and the unit in charge has to go out and cut it to get access to their own vehicle. This guy came in with bolt cutters, and then used the combat lock on the door he entered in. The only possible way a policeman without heavy ordnance got in with boltcutter, and the thief used a combat lock, was if there was another door that was padlocked closed, but not combat locked.
Tldr; yeah, you can still steal a military vehicle if you can sneak into an army base with a pair of boltcutters. It sure as shit won't be loaded, and if you pick the wrong one it might not even start up because they all breakdown regularly, and aren't clearly marked as such.
He tried starting two other tanks before driving off in the one he stole. National Guard maintenance in shambles.
His fault for not checking logbooks.
Losing keys to padlocks is why I took up lockpicking, don't want to get caught out again lol.