The Second Civil War has begun. Ignoring how succession happens, the American west coast (including Baja California & the Mexican state of Sonora) becomes an independent republic. Their border runs from southern Sonora, runs along the eastern border Arizona & Utah, then finally up beside Idaho until it comes to Canada.

Twenty-two years after the war began (this takes place in 2019), fighting has evolved into something like it has with North & South Korea, with nuclear weapons preventing the return of invasions or conventional warfare. For this border I described, what would the Western Republic need to monitor, patrol and protect this stretch of land? And with the Rocky Mountains serving as a natural barrier, how would this affect it?