Here's what's going on with the 50 American nuclear weapons stationed in Turkey

As tensions in northern Syria escalate following the withdrawal of U.S. troops from the region, reports suggest that the U.S. State Department is reviewing plans to remove 50 nuclear missiles from a military base in Turkey.

While Turkey is still a NATO partner, in recent weeks Turkish forces have begun shooting in the direction of U.S. troops.

"They're very powerful," said Jeffrey Lewis, director of the East Asia Nonproliferation Program at California's Middlebury Institute of International Studies at Monterey, of the nuclear weapons known as B-61 missiles.

"A B-61 comes in a bunch of different flavours…. and the biggest one of those is 170 kilotons," he added.

He compared that to the nuclear bomb that hit Hiroshima, Japan, in August 1945, which was rated between 10 and 20 kilotons.

Speaking with Day 6 host Brent Bambury, Lewis says there is no precedent for a situation like this. Here is part of their conversation.

How easy would it be for these bombs to fall into the hands of rogue actors or anybody else who would want to cause harm with them? 

There are security procedures in place. So fences and security measures that are around the part of the airbase. The bombs themselves are kept in vaults in the floors of these hardened aircraft shelters. And if you're actually to get one of the bombs, you'd have to be able to put in a code to arm it. 

So there are security procedures, so I would say it's not terribly likely. 

But what's important to keep in mind is that all of these procedures are really only designed to delay someone getting to the bomb, not really to stop a host country that wanted to seize them and do something with them. 

But that is the James Bond scenario that a bad actor gets a hold of a nuclear weapon. Just given the geopolitical situation right now, how likely do you think that is? 

I don't think that the Turkish government is going to seize the weapons. But, you know, when you work in the nuclear weapons policy area, you have all of these risks that you run every day that are very low in terms of their probability. 

But, you know, the fact is that leaving those weapons in place runs an unnecessary risk. 

Back in the early 1960s, the U.S. agreed to remove its nuclear arsenal from Turkey. That came out of the agreement with the U.S.S.R. That agreement was the one that ended the Cuban missile crisis. But how did the B-61s get into Turkey in the first place? 

As it turns out, there were other nuclear weapons stationed in Turkey at that time.

So, yes, the Jupiter missiles that we all know were there ... they came out in 1963, but there were half a dozen other systems, nuclear artillery, nuclear armed missiles and bombs that had been there since the late 1950s. 

And the United States has retained nuclear weapons in many of its NATO allies, including Turkey, continuously for the past 60, 70 years. And so at the end of the Cold War, most of those weapons came home. 

But the bombs to be delivered by foreign pilots sitting in the Netherlands, Belgium, Germany, Italy, Turkey, those all stayed because things were better with Russia after the Soviet Union collapsed. 

But the Bush administration in 1991 decided things maybe were not that much better. 

These are older weapons. They've been there since the 1960s. Do you assume that some of these bombs in Turkey have words like "Kiss it Khrushchev" written on them? 

[Laughs] Yeah, it's possible. But, you know, one of the interesting things that's playing out right now is that because the modifications are older ones, the U.S. is building a new modification of the B-61 called the B-61 mod 12. 

So it's the 12th different version of this bomb. The one sitting in Turkey are mods threes and fours, so those are much older. 

Eventually, all of the weapons in Turkey are gonna have to come home and be replaced by the new mod 12. And so maybe I'm one of the people who thinks like just bring them home and don't bother to replace them. 

Exactly. They could say that they wanted to modify them, then take them out of Turkey. Would that be easily done? 

Yeah, absolutely. In the early 2000s, I think in 2001, the United States pulled its nuclear weapons out of Greece. 

So the Clinton administration, followed by the Bush administration, decided that these things were not safe and they just put them on a plane and flew them home. And you could do that right now with the nuclear weapons in Turkey. 

What would be the diplomatic fallout there? Many people say that removing them would be really bad for the relationship with Turkey, which is already not very good. What do you make of that argument? 

I think it's a silly argument. What's really bad for the relationship is them shooting at us. You know, terrible things are happening, right? The relationship is in freefall and the nuclear weapons aren't preventing that.

It's not like having the nuclear weapons there is maintaining the relationship. It's completely collapsing. 

But Turkey remains a strategic point in the defence of Europe, in the defence of the Middle East. So if Americans take out their nuclear weapons, how long do you think it would be before [Russian President] Vladimir Putin starts talking about putting his in? 

Actually, at the moment, the Russians don't have any nuclear weapons based abroad.

And unless you count maybe Crimea, which they took, the worst part would be for Vladimir Putin to show up and, you know, get to check out our weapons that the Turks are holding on to for him.