Warships need electricity too..
IIRC, thermonuclear bombs are already made with lithium deutride.
Do you mean they're trying to build a thermonuclear bomb without the fission "detonator"? That doesn't make tons of sense to me, since I'd think the test ban treaty would realistically prevent creation of novel types of weapons (because it wouldn't be foolish to rely on a weapon for deterrence that you've never fully tested).