Today marks the end of an era. The geopolitical legacy of the 1980s has now disappeared. Today the last remaining nuclear arms treaty between Russia and the United States expires, with nothing left in its place. Some are predicting that this could set off another nuclear arms race that could see all the nuclear powers beefing up their nuclear arsenal, while other countries decide it is time for them to join the nuclear club.

It is sad to see the world slipping back into the dynamics of the Cold War, especially for someone like me who came of age in the 1980s. Back then, the U.S. and the U.S.S.R. had over 50,000 nuclear warheads between them, at one point even rising above 60,000. Today, Russia and America have a little over 10,000 nuclear weapons between them, which is a significant reduction. Other nuclear powers combined have a few thousand of their own (China now has about 600, while France, Britain, India, Pakistan, Israel, and North Korea all each have fewer). China has been ramping up its production, and with all constraints now lifted the United States and Russia may begin doing so as well.

The dynamics of nuclear weapons are changing fast, as new technologies (such as hypersonic cruise missiles) are either being deployed or are about to be. Nuclear defenses may prove to be ineffective given that these new technologies were specifically developed to evade them. Donald Trump announced a "Golden Dome" project to update America's nuclear defenses, but so far it remains mostly in the theoretical realm -- and even if it were complete and deployed, the newer weapons still might be able to defeat it.

Also, under Trump, the world is coming to the conclusion that America cannot be trusted anymore. The American "nuclear umbrella" guaranteed that smaller countries (mostly in Western Europe) would be defended by American nuclear weapons, meaning they had no need to develop their own. But with Trump's open disdain for NATO and his threatening to invade a NATO country's territory (Greenland), many nations are now reluctantly coming to the conclusion that America is not the trusted ally they have all relied upon since World War II. They may start to decide that having a few of their own nuclear weapons might be a good idea.

As I said, this is all pretty discouraging to someone who actively participated in many "No Nukes!" protests back in the 1980s. The world never achieved total nuclear disarmament, but it certainly headed in the right direction as a result of the last phases of the Cold War. Ronald Reagan essentially outspent the Soviet Union militarily, which was a key factor in the U.S.S.R.'s collapse. We could be headed back to another nuclear arms race again, where the U.S. tries to outspend both Russia and China in a similar way, with the outcome completely unpredictable.

The goal for those who still remain optimistic about nuclear constraint now seems to be to get a trilateral agreement worked out between the U.S., Russia, and China. However, China doesn't seem particularly interested in such negotiations, and Russia is already boasting it has deployed hypersonic missiles that could reach anywhere on the globe and defeat all anti-missile defenses. It's also preparing to deploy underwater drones capable of crossing oceans (faster than any submarine can) and detonating near coastal cities, to destroy them with a radioactive tsunami. Nuclear weapons could also soon be deployed in space. China has also developed similar technologically advanced delivery systems that could defeat any current defenses.

Vladimir Putin keeps hinting that he may just deploy nuclear weapons in his invasion of Ukraine, although so far he has not done so. Battlefield or "tactical" nukes with much smaller warheads have existed for years, although they've never actually been used by any nation.

Trump, however, seems convinced that his Golden Dome will be so awesomely perfect that nothing will be able to get through it. This is nothing short of being lulled into a false sense of security. If the missile defense system is perfect, after all, then why bother with nuclear arms limitation treaties? But much like Reagan's "Star Wars" missile defense system, the Golden Dome doesn't actually exist and even if it ever does, it will likely not be able to defend against the newer weapons systems being developed and even deployed.

We may be in for a couple of years of a new nuclear arms race before saner heads could prevail and new nuclear limitations agreements could get hashed out and ratified. This doesn't seem likely until Trump (and probably Putin as well) leaves office, however. America could rebuild the trust it used to have with the rest of the free world and emerge again as an ally other countries can rely upon. Again, that doesn't seem possible until Trump is gone, though.

From 1972 to today, nuclear treaties existed between America and the Soviet Union or Russia. That is the era that has ended. Reducing the world's nuclear arsenal from over 60,000 nuclear weapons to roughly 12,000 was a triumph of diplomacy that resulted in many different treaties limiting different aspects of nuclear weapons and their delivery systems. That whole framework is now completely gone. Trump and Putin don't seem eager to put anything in its place any time soon, and China isn't even interested in discussing the matter. So today might just mark the beginning of a second worldwide nuclear arms race, because the first era of nuclear limitation treaties is now officially over.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant