Introduce bacteria or viruses, get the entire area quarantined and effectively neutralize those facilities. Nobody in, nobody out.
This shit was gamed out years ago, decades even.
It used to be illegal for non-citizens to own land in the US. I remember in the 1950’s the local Japanese farmers leased their land on 99 year leases. There were a few native born Japanese who owned theirs but they were at least 2nd generation US. Sometime in the Ike years that law got dropped. Seems like we need to bring it back. Just like operation Wetback that deported most of the WWII vintage Mexicans who overstayed their permits after the war. We need it back.