Colonel James Hsu is a senior officer in the New California Republic Army in 2281, commanding NCR operations in the Mojave Desert from his headquarters at Camp McCarran. He is level-headed and soft-spoken, maintaining a calm demeanor despite recognizing the many problems plaguing his command, believing his behavior to be a necessary part of being a leader and the only real response to circumstances beyond one's control. Hsu knows how to use force to solve problems, but prefers diplomacy whenever possible, as opposed to his counterpart, the hawkish Colonel Cassandra Moore, or the NCR Army's chief, the gung-ho General Lee Oliver. Ambassador Dennis Crocker recognizes this and appreciates it, preferring to turn to Hsu over Moore in a tense situation where diplomacy might still be possible.
Hsu displays considerable understanding of the political and military situation in the Mojave, recognizing the difficulties the NCR faces. He cares a great deal about his soldiers and Rangers put under his command and works steadily to better their situation. His combination of high competence and dedication with a great deal of modesty has made him well-liked by his men, drawing the ire of General Oliver, who may see him as an up-and-coming rival. Craig Boone speaks highly of the colonel, and remarks that if it weren't for General Oliver's interference, Hsu would have already been a general by 2281.
In dialogue originally intended to be heard after the Second Battle of Hoover Dam but still available in-game while the battle is going on, Colonel Cassandra Moore says that upon learning of the NCR's success in the Mojave, her superiors first turned to Hsu since he was in command of operations in the area, but he denied having anything to do with the victory. As a result of his modesty, Hsu got passed over for promotion and Moore was promoted to brigadier general instead.
Colonel Hsu is commander of all NCR Army operations in the Mojave Desert, while Colonel Moore commands the garrison at Hoover Dam. Thus Hsu has higher authority than Moore, despite the two of them being the same military rank.
General Lee Oliver outranks Hsu significantly, but Hsu is designated in dialogue as being in command of all NCR forces in the Mojave. Oliver has moved in to command the situation personally, but is exercising his rank to do so. As the NCR Army's highest-ranking officer, his official position is leading the whole Army.
↑Craig Boone's dialogue: "When he looked at you, you could see he understood. After some of the things we'd seen, that meant something. What I heard, he'd be a general right now if Oliver didn't know the president."
↑Colonel Moore's dialogue: "The brass was particularly surprised by the lack of domestic threats in the area. They were prepared to spend months pacifying known troublemakers. When they found those threats absent, they turned to the man in charge of the area, but Hsu being Hsu, he denied having anything to do with it. So now the men have to answer to Brigadier General Moore, and both they and I have you to thank for it."