The ability to order the deployment of Cluster Mines by air was a basic promotional choice available to all Chinese generals at rank 3. The mines were taken to their target by a supply aircraft and dropped inside a bomb. When the bomb exploded, the mines would be scattered over a fairly wide area. Mines were invisible to most enemy units, and could stop an armoured attack in its tracks - they were used heavily at key 'chokepoint' areas where enemy forces would be funnelled through a relatively narrow area.
But it had some counters too. Most field detection units could notice them. Also, Construction Dozers and Workers were equipped to automatically detect and disarm the mines as they passed by them. Because of the explosive nature of the mines, they can be inadvertantly (or deliberatly) detonated by firing at them with explosives (Bullets to not cause them to detonate). This means that a squad of tanks that is near a detected minefield (Or in proximity to a suspected one) can be ordered to fire on the area by the general to detonate them at a distance- care still had to be taken to ensure they were cleared.
A plane can be called in to drop cluster mines every four minutes.
Behind The Scenes
It is similar to the mine drop from the Brotherhood of Nod