Justin Hammer represented one of the many enemy factions who attempted to replicate the Iron Man armor but failed in all areas. The test pilot in the Hammer suit barely survived being twisted one-eighty degrees around. The footage of this incident was shown publicly by Tony Stark during his hearing with Senator Stern to prove that there was no need for him to hand over the Iron Man armor to the U.S. government. Hammer was so jealous of Stark that he broke Ivan Vanko out of a French prison after Vanko attempted to kill Stark at Circuit de Monaco. Justin wanted Vanko to improve on his developing suits so that he could upstage Stark at the upcoming Stark Expo. Vanko agreed to do so, if Hammer brought him his parrot he left back in Russia; Hammer agreed and fulfilled his end of the bargain. However, Vanko instead modified the armors to be remote-controlled drones.
When Hammer learned that Stark was in disgrace after a drunken binge at his own birthday party and that James Rhodes had procured the Iron Man Mark II for the military, he offered up various weapons to augment the latter's armor. However, Hammer eventually discovered that Vanko was secretly siphoning company resources for his own armor. Hammer was so angry that he placed Vanko under house arrest. But Vanko freed himself, hanged his guards, and took control of the drones and the new War Machine armor when Hammer was unveiling them at the Expo, ordering them to target Stark. As he tried to regain control of the situation, Hammer was confronted by Pepper Potts and Natasha Romanoff, who demanded to know where Vanko was. When Hammer tried brushing them off, the latter grabbed him and forced him to reveal Vanko's whereabouts. Potts then called the police to have Hammer arrested. As he was being led away into S.H.I.E.L.D. custody, Hammer promised that he would have revenge on Stark and Potts.
After SHIELD fell, HYDRA saw Hammer as a opportunity to be one of their highly ranked business figureheads. With SHIELD's reputation as a terrorist organization revealed, HYDRA was able to get Justin out on parole. He was later approached by U.S. Secretary of Defense Dale Russ who informed him about the circumstances of his release and promised him a return to glory if he cooperated. Hammer Industries was later placed under both his and his sister Justine's control ,and together they joined forces with AIM.