Problems were still present this far into the development cycle, delaying deployment. The T-51 model power armor remained in development, with various production models being tested in combat conditions at Fort Strong in Massachusetts, troubleshooting the design. However, the invasion quickly bogged down as the T-45's aging design proved insufficient to overcome the Chinese defenders. In 2074, American T-45 model D power armor units, mechanized cavalry, and infantry divisions invaded mainland China. Various modifications were developed and tested using it as basis, including the MP-47A unit, featuring an autonomous medical delivery system and rudimentary onboard AI. In the meantime, the T-45d became the symbol of American might. However, the ambitious nature of the project led to many delays and it took nearly ten years to complete the development cycle. By 2069, it was the largest contract of the largest defense contractor of the United States government. Meanwhile, West Tek continued developing a superior model, designated T-51. In a way, China engineered its own demise, as the deployment of the T-45 also led to the development of the West Tek power armor frame, the basis on which all subsequent armor was manufactured.

Anticipating this move, the military invested in the development of electromagnetic weapons to counter the threat should it arise. China rushed to develop its own version, but it was years behind the United States. Although lacking in mobility, this early model allowed soldiers to carry heavy weapons into combat, becoming key to countering masses of Chinese infantry and tanks. In 2067, the first West Tek production model of powered infantry combat armor designated T-45 was rushed to the frontline to defend against the Chinese attackers. The invasion of Alaska in winter of 2066 forced the military and its contractors to cut corners and come up with a stop-gap solution. It further strained Sino-American relations, after the United States refused to share its crude oil reserves with the Asian superpower. Crude, but effective, the design was unveiled to the world in the summer of 2066. The most important achievement of this early stage of research was the development of a fusion cell. While early prototypes were unsuccessful, lessons learned in the process paved the way for future advances in military sciences, construction, and fusion.

Mechanized cavalry units provided with them would retain the mobility of a soldier moving on foot while giving them the ability to use heavy weapons with ease. With the resource crisis severely limiting the ability of the United States military to deploy combat vehicles, especially tanks and other types of armor, it began research efforts to create self-powered combat suits in August 2065.

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