Assumptions:
- Both Empires want the other to become their empire.
- Both Empires cannot use direct conflict due to Mutually Assured Destruction.
- The PR people of each empire don't want to admit ethical mistakes or inhumane actions, despite their willingness to do shady crypto-military things.
- There are no Edward Snowdens.
Should these governments disclose their ability to manipulate weather? #The Case For No If
The Case For No
If one empire crumbles because of drought, floods, etc., it can be sold to people as an (legal) "act of God," and the relief effort for that can be used as a method of takeover. We actually saw a glimpse of "using human rights to take over" with the Russian Annexation of Crimea.
The history books would simply blame an empire's collapse on nature, not on the other empire. The conquering relieving empire would be seen as taking the moral high road. Besides, weather manipulation could be a weapon neither side expected to see from the other, and in this situation, each empire would leverage even small advantages.
The Case for Yes
#The Case for Yes IfIf a population found out they switched their empire for the other empire because of shady crypto-military operations, that could cause a former peaceful group into a revolutionist entity. Revolutions are generally bad things, as you can see in Syria.
Besides, an empire can use the other empire as a scapegoat for all the bad weather they experience, which could lead up to war or other reparations. However, both empires can play this game, and it may devolve into either each country officially controlling their own weather or playing the blame game.
The Verdict
#The Verdict TheThe Case for No seems more compelling. I would see these empires not disclosing their ability to manipulate the weather. It's too good as a secret to tell anyone.