People seem to be getting themselves all worried about this but we've actually been able to "do nuclear fusion" for many years - the breakthrough is that they've managed to create a fusion reaction that
created more energy
than was used to trigger the reaction. Obviously it's useless as a power source if it takes more energy to ignite and contain the fusion reaction than it actually churns out.
Also as far as I understand it... it eliminates the risk of meltdown, because as soon as fusion reactions become uncontained they very quickly just stop - being contained is part of what allows the reaction to occur. And fusion reactions don't create radioactive waste or fallout so aren't a concern anyway.
As for whether or not cold fusion BOMBS as a possibility is scary... well that's a little more tricky. They wouldn't be any more destructive than current high yield nuclear weapons, the difference again would be that they're "clean" - no nuclear fallout. The positive of that is obvious - even in a full scale nuclear war with cold fusion weapons, there's no pollution or nuclear winter. But that, oddly enough, is also the drawback ... Mutually Assured Destruction is a huge part of what stops a nuclear war kicking off, and part of Mutually Assured Destruction IS the knowledge that nuclear fallout would destroy the world.
In other words... if two nations create clean fusion nukes, they're MUCH more likely to actually use them on each other. Again the plus side is you only have to worry about that if you live in one of the involved countries. Also means you're probably safe if you get the heck out of major population areas before the bombs drop
.