In the past, weapons development always resulted from war, and in the midst of that war to adapt to the changing battlefield to gain an advantage over the enemy. Part of a war is development of weapons. Better weapons than the enemy. Stronger, faster, more reliable ways to engage in war.
The Cold War was a war without battles. We fought over who had the advantage on the battlefield even when we didn't have a battlefield.
But the point I'm getting at is that nations feel threatened when another nation is stockpiling weapons, building up their armies and navies, and positioning them against other states. And for good reason.
In the past when a nation was building up their armies they invariably went to war. Perhaps to justify the build up, or maybe because of hubris over their great strength. For example, Germany built up a strong, mechanized military leading up to their invasion of Poland and Czechoslovakia. The Allies had to respond in the midst of war to build up their own mechanized forces to match their abilities.
We see this still today. We see nations nervous of other nations arms programs. Pakistan built their nuclear program because India has one. Iran may be seeking nuclear weapons because Israel has some. Russia is protesting the missile systems the US have been installing around their borders.
But the whole world is nervous because the USA continues to build up its military strength year after year, developing newer, more awesome weapons of mass destruction. Inventing new ways to kill people all over the world. We have 24 hour surveillance of every corner of the globe, and a military presence in every theater. They look at us and ask themselves why we have so much power. We call it a defense force but we're so far away from our borders. We're in their country.
So the Cold War continues. People feel threatened by the state with a massive military presence.
John Howard Yoder said this:
Christians whose loyalty to the Prince of Peace puts them out of step with today's nationalistic world ... are not unrealistic dreamers who think that by their objections all wars will end. The unrealistic dreamers are rather the soldiers who think that they can put an end to wars by preparing for just one more. ... Christians love their enemies not because they think their enemies are wonderful people, nor because they believe that love is sure to conquer those enemies. ... The Christian loves his or her enemies because God does, and God commands His followers to do so; that is the only reason, and that is enough.(link)