Before joining the International Fleet, Vaganov served as a battle cruiser commander in the Russian navy.
Colonel Vaganov ordered Mazer Rackham to his office while reviewing his military file. He and Mazer made small talk about life at CentCom and how Mazer communicated with his wife Kim Arnsbrach, who was still on Luna. However, Vaganov suspected that he put his personal life with Kim above his soldier duties, which he saw as a good quality in an officer. After discussing more of his record, Vaganov stated that he thought the Fleet would lose the coming war because of incompetent leadership. He revealed that he had set up the officer socials to identify soldiers like Mazer, who couldn't stand the bureaucracy of it all.
After mentioning that he believed Mazer's breach team was the best in the Fleet, he asked what Mazer thought of the Gravity Disruptor device. Mazer expressed his concerns with the device, and then showed Vaganov his design for a nanobot shield. After telling Mazer not to share his ideas with junior officers, Vaganov asked Mazer to bring the designs to him first. Vaganov then informed Mazer that he would begin testing live Gravity Disruptor charges the next day, when he had just listed the various problems with the device. Mazer protested, but was shut down by Vaganov and dismissed.
Later, Vaganov was in a meeting with the director of Gungsu Industries, Hea Woo Han. During the meeting, he called Ukko Jukes, the Hegemon, and showed him a series of holos of the breach teams testing the Gravity Disruptor. However, the clip of Mazer's team was edited so that the explosion did not look as violent and Shambhani, who lost a leg due to the shrapnel, did not make an appearance. Mazer, who had been waiting by the door, was told by Vaganov to wait in his office. After returning, Vaganov was confronted by Mazer when he realized that the defective cube was deliberate, giving the most skilled breach team the harder test. After some discussion of the matter, Vaganov insisted that the nanoshield design would be developed by Gungsu, against Mazer's objections. When Mazer refused to accept a liaison position with Gungsu, Vaganov ordered two MPs to take Mazer into custody.
Later, Mazer requested to meet with Vaganov with new information. Once in Vaganov's office, Mazer explained the images in the email he recieved, showing Asteroid 2030CT colonized by Formics. He expressed his concern that the asteroid may be used as a missile to be launched at Earth. Mazer suggested that the International Fleet form an assault team specializing in asteroid combat.
After Vaganov asked to see the rest of the images in Mazer's email, he noticed that all his other correspondence were missing. Vaganov thought this meant he was concealing the fact that he was talking about Vaganov to others, which Mazer denied. Paranoid, Vaganov revoked Mazer's net access and declared that he would handle transferring the information to the rest of the Fleet. To avoid Vaganov's bureaucracy impeding the sharing of the information, Mazer signed into his forum on the holofield and sent the information out to the junior officers of the Fleet. Furious, Vaganov assigned Mazer a MP to guard him at all times and dismissed him.
In order to discredit Mazer, Vaganov did two things over the following week. First, Vaganov found a health officer, who would not recommend Mazer for combat due to previous injuries. Secondly, Vaganov ordered Nardelli to incite a fight between Mazer and him in order to tarnish Mazer.
Vaganov earned a promotion to Rear Admiral once he realized his position was a dead end job during war time, and he requested command of a warship. On route to the ship being built for him, Vaganov encountered Mazer, telling Mazer that he had learned about his unique past during the First Formic War. Vaganov then requested that Mazer help him spy on Colonel Li and Rear Admiral Zambassi in return for a reassignment to a more interesting job. Mazer refused, as he did not want to betray his commanding official.
After Zembassi decided to change the ship's destination to the asteroid Castalia and they had arrived there, Vaganov confronted Zambassi with the problems in his plan, as he believed that by blowing up the Formic-created atmosphere around the asteroid they would destroy any discoveries about the bioengineered Formic bugs that could be obtained. Mazer and Zembassi were against the idea of sending in men to the asteroid, as the volatile atmosphere presented a high risk, but Vaganov had already conferred with the Polemarch and Strategos, and after detailing the fact that the cadet program was secretive and nobody would know if all the cadets died on the asteroid, Vaganov took his leave back to his quarters, and his plan was implemented.
Two days later, Vaganov visited the docking bay to see the breach team off. After Bingwen's destruction of the asteroid and discovery of the Hive Queen daughter-general, Vaganov was promoted to vice admiral, making him the commanding officer of the ship.
Vaganov was not a fan of bureaucracy, a trait he shared with Mazer. He knew exactly how commanders and junior officers would respond to certain situations. However, he was a corporate sellout to Gungsu Industries and did not respond well when his orders were questioned.
He was also extremely paranoid, thinking that the mere absence of Mazer's emails meant that he was discussing him with others.