Man-made nuclear fusion is not self-sustaining, requires massive infrastructure to ignite very little of material.
Nuclear fission of unstable isotopes is self-sustaining chain reaction that converts a lot of matter into energy without much of hardware - just put some sub-critical mass of Plutonium into a sphere lined with conventional explosives.
Well, of course that's always been true in the past, but isn't "ignition" precisely the point at which it becomes self-sustaining? Isn't that the distinction between "ignition" and not "ignition"? I mean, you're not the right person to ask (you apparently think plutonium is a brand name), but maybe somebody reading this understands the issues.
You don't even need explosives to get a self-sustaining nuclear fission chain reaction if you don't want a bomb; Harry Daghlian did it accidentally, Fermi did it underneath Stagg Field in Chicago in 01942, we do it routinely to generate electricity, and 16 fossil natural nuclear fission reactors have been discovered in Oklo. The explosives are only there to keep a rapid chain reaction from driving the pieces apart before you get enough yield for a weapon.
It's true that the NIF would not make a very useful bomb, being difficult to deliver to enemy territory even by ship, and probably inflicting more damage on the funding agency than the destroyed enemy city. But a significant part of that is non-recurring engineering costs, and it's probably possible to miniaturize it to a significant degree.
I read Freeman Dyson's autobiography recently, and he claims (contrary to the report of continuing DOE research in the Wikipedia article) one of the things they stopped working on in the 01960s due to the arms treaties was specifically hydrogen bombs that didn't require fission igniters.
Ignition in the case of ICF means that, for the brief time while the shockwave from the initial laser burst is still keeping the plasma together, you get to fuse all of the D+T in your pellet. Once the initial velocity is lost, the high-temperature He dissipates away.
Not ahcieving ignition means that the plasma cools too rapidly and the fusion reaction stops even before the brief microseconds of inertial confinement are lost.
Perhaps if you could deliver enough energy to a large enough pellet, you could use this to build a bomb, but today it is far too small for that, and the reaction wouldn't work with a larger fuel pellet (the geometry that allows the extreme pressures needed for fusion would not be easily achieved with a larger pellet, since even the wave-length of the laser is relevant at this level).
Nuclear fission of unstable isotopes is self-sustaining chain reaction that converts a lot of matter into energy without much of hardware - just put some sub-critical mass of Plutonium into a sphere lined with conventional explosives.
See also: https://en.wikipedia.org/wiki/Pure_fusion_weapon