I could easily see where a China somehow gets fissionable material that fits the profile of Russian nuclear reactor. Fashions a bomb out of it and hands it off to Arab terrorists. The Chinese are so good, so cut out, that it's pinned on these crazy Muslims while it was the Chinese all a long. And a rogue element, not even the official Chinese government.
Real problem is that crazy groups can engineer mega terror events. Governments need not act directly. They will act untraceably. As you say..... No credit will be claimed. That would spoil all the fun, laughter, clinking of cocktail glasses in Beijing and Tehran
I'd say, "go to the head of the class, grasshopper," but you are already there.