Scenarios - Triggers

I think to enhance details in scenarios, we need triggers. Triggers occur when you do something that causes another event to occur, for example:
"If China takes Mongolia, a Russian army will spawn with 10 units of infantry."
Or with diplomacy
"If the US allies Free France, 3 US O.S.S units spawn near Free France's capital."
"If Mongolia takes Taiwan, 5 units of Patriots appear in Taiwan."
Those are just some examples. I'm not entirely sure if this would require changing the engine or just adding to the game engine, so here I post!