This is really the only option America has if Japan or South Korea want US nukes based there
As the crisis over North Korea's nuclear program heats up, some are calling for the return of American tactical nuclear weapons to South Korea, or possibly basing them in Japan.
And while the notion of America deploying so-called "tactical" nukes to South Korea or Japan may send arms controllers into a fit, there are actually few options if the US does get the nod from Asian nations.
During the Cold War, the United States had a variety of delivery platforms for the tactical nukes. There were artillery rounds like the W48. There were missiles like the MGM-52 Lance. There were also air-dropped tactical nuclear bombs.
But arms control agreements through the 1990s and later cut America's options way down — no more cruise missiles, artillery rounds or ballistic missiles were allowed after the treaties were signed, so today the only US option available other than full-on doomsday weapons are air-dropped bombs.
If Tokyo or Seoul want US nukes there, America could deploy the B61 bomb. According to the Nuclear Weapons Archive, this bomb has been in service with the United States since 1966 – meaning it's got over 50 years of service. Its most notable feature is its versatility thanks to "dial a yield" technology, meaning it can provide the force equivalent to 300 tons of TNT all the way out to 340,000 tons of TNT.
Any combat plane in the United States arsenal has been fitted at one time or another to use this bomb. Five versions of the bomb are currently in the stockpile, the B61 Mod 3, B61 Mod 4, M61 Mod 7, B61 Mod 10, and B61 Mod 11. A sixth version, the B61 Mod 12, is in development, adding the ability to use an internal guidance system, according to Popular Mechanics.
Deployment to South Korea and Japan would place the weapons next to the most likely delivery platform for tactical nuclear strikes: F-16 Fighting Falcons. The 8th and 51st Fighter Wings at Osan and Kunsan Air Bases in South Korea and the 35th Fighter Wing in Japan combine for five squadrons of the planes.
The deployment of this system does come with the need for added security. During the Turkish coup of 2016, the security of the nukes became a concern, prompting their eventual evacuation.