This whole issue was argued over in another thread, but I have huge issues with these guys.
A) What were they doing in DC anyway? Canon talks about the physical battle between US and Chinese troops in Alaska, but never mentions it in DC, which is fine, I suppose. Maybe that information was lost, who knows, but DC is landlocked, and would be difficult to get to. Now, assume that it was a small force, infiltrating. That'd be fine, except for the seemingly endless supply of Chinese Pistols, Chinese Assault rifles, and Chinese Officer's Swords (wtf). This seems to indicate an invasion-sized force, yet we see no signs of an invasion. There'd be more Chinese descended people running around the wastes, speaking Chinese. Yet we only find a single grouping of Chinese ghouls, what happened to the rest of them? They died in the bombs? Maybe, but some had to survive, right? Not just some small grouping, if it was an invasion-sized force a lot would have survived, right? It makes zero sense.
Now you have the Chinese ghouls, for two hundred years, hiding out in some building. Why didn't they try to go home? Why do they just sit there for two hundred years? The main character from the second Fallout managed to find a ship that was functional, why couldn't they?