NK is more independent from China and a thorn in their side than you might think. NK's nukes can fly to Beijing faster than they'll fly across the Pacific. Korean nationalism is also strong in NK and they have no desire to be China's puppet given the historical implications. NK's greatest years where when the USSR/Russia was strong and they could count on Soviet economic assistance and military counterweight against China.
Plot twist. America hacked North Korea’s nuclear defense system, and launched their nukes at Beijing from North Korean soil, to frame North Korea.
To all outside observers, this looks like North Korea did it. But Beijing is now turned to glass, and the Chinese command is transferred to the military division in Chengdu. The world is tense, as it awaits China’s retaliation.
However, China doesn’t fall for the bait. They begin their investigations in earnest, and discover the true mastermind behind the nuclear attack: The United States.
World War 3 begins. China launches 1000 ICBM missiles at the United States. Thus ending all known life as we know it on American soil. The American military counterattacks and launches all their nukes at China. Both sides are turned to glass.
The world gasps at what just happened. Russia now proceeds to take over the world. Well played.
Romania also had guns on the border with USSR, but it did not prevent USSR from spending all of its anger for this geographic region on the tiny Albania.
Chauschesku was bas a bastard, bit it was their bastard, unlike Enver Hoxha.
In all scenarios I see, it will work the other way around. I doubt that NK military would move a centimetre without Beijing's explicit authorisation.
In any big war, China will use NK as a cannon fodder.