It’s a common thing to do if you are about to abandon your consulate or embassy - torch your secrets and communiqués - particularly if your home country is about to do something to piss off the country you’re in. Goes back at least a few hundred years.
One reason not to do it until the very last minute is that it signals the host country that something may be coming.
Perhaps the goal is like Nixons with respect to North Vietnam, to make the opponent think you are capable of something horrendous so that it backs off?
Your tag line is a clue.
When the Chinese forced down our reconnaissance plane, we did nothing.
I suspect they will try something similar only more aggressive.
Probably involving the navy operating in that part of the world.
I hope not.