Sure, but better weapons than nuclear are being developed at all times, recently, I can't remember which country, probably US, were working on even more powerful weapons which were meant to be using Tritium, as far as I remember...
The US has gotten rid of all of its old A bombs(to the best of my knowledge), while russia still has some of the old style bombs all modern nuclear bombs are thermonuclear, which use tritium, a radioactive material(hydrogen also why they are known as a hydrogen or H bomb). While it has a VERY short half life it IS still radioactive, meaning what you are describing would be a nuclear bomb.
While the US has some other very interesting bombs the only other bomb i know of that the US is building with tritium is a nuclear bunker-buster. As far as conventional bombs go the US already has its answer for a city buster(at least a small city, certainly any base, even a VERY large one) which is the MOAB(Massive Ordinance Arial Burst/Air Blast) which is a ~40k lbs bomb/11 tons TNT yield(our smaller nukes do 30-50 ton TNT yield as an idea). Russia supposedly has one more powerful but i dont know its weight/yield or hell even its name.
Anyway considering the incident(s) that have gotten the US into two different world wars, and what set them off, i dont see how anyone can be so optimistic as to say that this COULDNT start a world war. Wars have been fought for less :/.
As for who gassed who lets hope the UN investigators find out. But frankly im not willing to take EITHER side at their word. Someone gassed someone, they DO need a lesson. I just hope the world teaches the lesson to the right people and that it doesnt start a war to end all wars....(as if that could ever happen while the human race survives...)
In the end what i know is this: whats going on over their scares the shit out of me. This very well COULD start a world war, and if so their are 0 guarantees it will stay conventional. Add to it that tensions are at a boiling point in several other countries over various things and this war could end up being a free for all. Israel has been at war since its inception, guaranteed IT gets into a major battle for its life. North/South Korea probably goes to war with the US/UN distracted. China if it gets involved makes a grab for Taiwan(damn near guaranteed) maybe goes after Japan, maybe goes after Russia, maybe all of the above. Russia if it gets involved....who the hell knows, their Russians. Analysts have been trying to predict what will happen in Russia with a damn near unlimited budget for the past 50 years, and have gotten more wrong that right, and we knew/know so many Russian secrets that even most of their own citizens dont know its not even funny. Even with MASSIVE amounts of inside information we couldnt predict them then, let alone now. In the end i really only see it going one of two ways. A small fast scirmish with a few missles fired or bombs dropped....or a giant fuck fest, and not the good kind either.