The US first prepared to deal with terrorist nukes in the 1970s

You may think that terrorists getting their hands on nuclear weapons has been a concern only since the Berlin Wall fell and the Soviet Union collapsed. Well, you'd be wrong — off by well over a decade.

The thought of terrorists getting nukes has been on the minds of the Department of Defense for a long time. While today's worries center mostly around a certain rogue state pawning off a nuke or some of Russia's nukes mysteriously walking off, back then, the concern was more along the lines of terrorists trying to sneak in and steal nukes.

Now, before you panic, even if you have a nuke, like the B61 gravity bomb, you can't just set it to go off. There are a lot of measures in place to make sure it only detonates when authorized. One of the most important tools in this regard is the permissive action link. It actually had its genesis in the 1960s, when the United States had forward-deployed nukes to be dropped by the planes of NATO allies.

Now, if you saw the 1996 movie Broken Arrow, you saw a very Hollywood-esque version of how the device works. You need to enter the right code for the nuke to be armed. Enter the wrong code and the B61 becomes a 716-pound paperweight.

The permissive action link, though, is a defense measure in place just in case the bad guys actually get their hands on the nuke. The better solution, of course, is to make sure that they don't get their hands on it in the first place. This is where lots of armed security comes in, equipped with the latest technology to detect intruders.

Watch the video below to learn how the Defense Nuclear Agency planned to deal nuke thieves in the 1970s.