If Hollywood wants to produce a movie about war/ show military operations etc. they can let the D.O.D in on the production/writing. If the D.O.D is allowed to co-write the script, the production team basically get to use equipment and military locations for free.
This is the part of the deal that's out in the open. I'm certain of that there's a lot more going on behind closed curtains.
China had/has sanctions on import/export of coal, some petroleum products as well as some textiles. I haven't read any statements about the their sanctions from China, so I don't know why.
It seems to come from a UN resolution, but I'm not sure