Have you ever spent a thought about the usage rate of nuclear weaponry, I mean real usage in battle. We can count nukes used for real in combat using the fingers of a single hand: 2 [two]. How many nuclear weapons have been produced in the world? Some estimates say that in 1985 there were more than 60,000 nuclear active weapons ... This would mean a usage rate of 2 / 60,000 =[TABLE="width: 94"] [TR] [TD="class: xl33, width: 94, align: right"]0,0000333333[/TD] [/TR] [/TABLE] Or 1 nuke used every 30,000 nukes produced. Considering costs, one could infer that the nuclear weapon is the less efficient and more economically expense weapon ever ... Eh no. Since the existence of such an arsenal has practically avoided WW III and so the return of the investment in nukes is not represented by direct earns, but by avoided losses.
And that is the main reason why so many were made, and are still in service. With conventional weapons, it becomes to tempting to use them someday. When you spend a lot of money building Battleships tanks, and Bombers, it becomes tempting to use them to take over land. And when the enemy has the same thing, most of the damage is minimal and constrained to the military of the other side. When the weapons can destroy entire cities in a single use and kill huge numbers of civilians (especially the leadership) it becomes much less appealing of a weapon to use, and is then only used to ensure that the threat of your weapons prevents them from being used against you.
Or in the 21st Century especially when looking at California, use them to take over water. I need to compare California's National Guard to Oregon's and Washington's National Guard.