[dharmab]

Isn't tritium used in fusion and a potential weapons material?

[devmor]

It's a fission yield booster. It's as much of a weapons material as charcoal is.

[mlyle]

It's not controlled. It does help boost some fission weapons. But it's not the hard part or critical piece of producing a nuclear weapon, and you can get by without it.

To illustrate how little it's controlled-- I have a little bit on my keychain as an alpha source with a phosphor so my keyring always glows.