The United States (and allies) have already used rain seeding, river damns, and a number of other techniques for damaging adversary nation's economic and agricultural abilities. It's even a relatively common practice in geopolitics (India uses the Indus river as a carrot/stick against Pakistan).
I'm pretty sure that that is common knowledge and openly discussed among people who care about such stuff.
Would you provide more information in the form of a reliable source?
"After World War II, the U.S. military bombed dams in North Korea and North Vietnam to destroy the communist governments’ electricity and irrigation infrastructure. This was, until the Iran-Iraq War, the final occurrence of such soggy tactics. In 1977 the Geneva Conventions specifically outlawed the targeting of water infrastructure in wartime." [2]
[1] https://en.wikipedia.org/wiki/Operation_Popeye [2] https://medium.com/war-is-boring/dam-warfare-3da6ee24518a https://en.wikipedia.org/wiki/Bombing_of_Vietnam%27s_dikes