The threat of nuclear war hasn’t been so prominent in the national consciousness since the fall of the Berlin Wall. But Donald Trump’s tweet, where he cleverly uses the threat of nuclear war to imply that Kim Jong Un has an erectile dysfunction, has brought the threat of nuclear doomsday back into the public consciousness.

North Korean Leader Kim Jong Un just stated that the “Nuclear Button is on his desk at all times.” Will someone from his depleted and food starved regime please inform him that I too have a Nuclear Button, but it is a much bigger & more powerful one than his, and my Button works!

— Donald J. Trump (@realDonaldTrump) January 3, 2018

He’s had the rhetoric to back up these tweets, too, suggesting that we should drastically increase our nuclear arsenal (this came, of course, after he said that nuclear proliferation is the “single biggest threat” facing the world right now).

Don’t let all of the scary talk about nuclear holocaust distort your handle on the situation, though. The fact of the matter is that the possession of nuclear arms by multiple countries around the world is actually a good thing. That sounds counterintuitive, but let me explain.

Nuclear weapons are the reason wars don’t happen. Over the decades since WWII, there have been exactly zero wars between the great powers of the world, and that can easily be explained through the threat of Mutually Assured Destruction, or MAD. When two powers, like the Soviet Union and United States, know that war could potentially end the world, then of course they’ll do everything in their power to make sure that doesn’t happen.

Think of it this way. Imagine how deadly the Cold War would have been if nuclear weapons didn’t exist. The US and USSR would certainly have gone to war, and millions upon millions might have been lost, nuclear bomb or no. Now compare that to our reality, where nukes do exist and war never happened because of it.

It’s for this reason that China feels like it must behave very delicately in claiming the Spratly Islands, or why Russia denies it forcefully annexed Ukraine when it clearly did. These countries need to avoid open conflict with other countries of their military caliber, or else it might erupt into a world ending catastrophe.

This means that powerful countries can’t bully their way through situations and need to tread lightly, encouraging diplomacy and cooperation. We shouldn’t be shying away from this and trying to destroy the devices that created this circumstance.

This is why we should be skeptical whenever a politician talks in absolutist terms about the danger of nuclear weapons and about disarming the world of them. This kind of talk means they either don’t understand the situation or are knowingly pursuing an idealistic but popular policy to gain support from voters.

That being said, MAD only works because of brinkmanship, or the willingness of country’s leaders to take a dangerous situation to the very edge before pulling back. This has yet to fail the world yet. After all, we’ve never had a nuclear war? But it only takes a few crazy people willing to take it a little too far to misjudge the other side and accidentally step over the edge.

So, in other words, the system works until it doesn’t.