The process of becoming ready for conflict or war is militarization. Sometimes militarization refers to making a civilian organization resemble the armed forces—with uniforms or weapons, for example.
When a country prepares itself for war, that's militarization. And when military resources are sent somewhere—to the site of a natural disaster or a political demonstration, for example—that's also militarization. A more systemic kind of militarization happens when a city's police force acquires military-grade weapons and uniforms, or uses military tactics instead of traditional community policing methods. The Latin root of militarization is militaris, "of soldiers or war."