That's a thing he is exceedingly unlikely to do in any case. But last I heard, the Pentagon works for him.
The whole proposal is grandstanding. They couldn’t even put the words in to prevent him from removing troops from SK because they know they cannot do so. The best they could do is say Trump has to discuss it with the Pentagon first.
Since Trump is the CIC that is a non starter.
During WWII, didn’t Patton have to get approval from the privates under his command before he could give them orders?
/s
I suspect there will be an ostentatious removal of nuclear assets in South Korea, ships in port will leave and not return but troops pulled out? a token amount, perhaps, but troops will stay there. Those troops speak to China, not really to Norkea. Norkea would NOT invade without an OK from Peking.