Thanks for posting this. I was not aware of this.
Since they had their own atom bomb program they knew some things and had researched others.
Our guys knew about their program and they knew about ours. Sorge, Stalin's spymaster, found out about the Japanese spy in the Manhattan Project from his other spies ~ the Rosenberg crowd weren't the only Soviet spies it turned out.
Stalin informed Roosevelt, and Roosevelt sent our guys to take him out ~ alas, he fled before being captured because, as it turns out, the Japanese had spies in either our top level of command or inside the Kremlin.
My understanding is the spy for Japan was an Englishman. No idea who Stalin's other spies were who blew the whistle on him ~ like Stalin had a lot of spies in that program ~ highly trained and educated people who were there to make sure it worked ~ not just to steal the secrets.
Folks had a lot riding on the development and construction of workable atom bombs. FOr the most part they all kept it secret from the public at large.