Project 7734 was a secret project by the U.S. Military to defend the planet against alien incursion by any means necessary. Led by General Sam Lane, the group's distrust of the newly-restored Kryptonian civilization on the planet New Krypton caused them to begin work on an preemptive attack. This attack led to the destruction of New Krypton, as well as a full-fledged war between the Kryptonian and Human militaries. (Comic storylines: Superman: New Krypton, The Last Stand of New Krypton, War of the Supermen)
The project is also referred to in the Superman & Lois TV show, where Sam Lane of an alternate reality leads Earth's forces against the genocidal Superman assaulting their planet, and hands Captain Luthor a dog tag with the Superman symbol, with "Hell" written on its back, before dying. Upon being inverted though, it reads "7734". Sometime after reading the tag and becoming upset with Superman, General Lane calls Lt. Rosetti and tells him to set up a contingency protocol against the hero called "Project 7734". Under the project, the military develops weapons utilizing Green Kryptonite.