Final answer:
The creation of the U.S. Northern Command marked a pivotal reorganization of the U.S. military's defense strategy, focusing on the security of northern regions and complementing other Cold War defense initiatives.
Step-by-step explanation:
The creation of the U.S. Northern Command was important because it symbolized a significant reorganization and modernization of the U.S. military's command structure, emphasizing the integration and coordination of defense capabilities. It was part of a larger trend during the Cold War where the U.S. military sought to establish sophisticated command and control systems. The Northern Command would presumably be responsible for ensuring the security of the northern regions of the United States, operating alongside other defense initiatives such as the Strategic Air Command and bolstering America's defense infrastructure.