Ukraine Lessons Learned

December 22nd, 2025

Over the past several weeks I’ve listened to a number of discussions concerning how to defend both Europe and Taiwan, in light of all that we have learned in the Russia - Ukraine war, with lots of talk about the changing nature of warfare. Which leads me to ask a simple question:

What is the number 1 lesson learned from the war in Ukraine? Hint: it’s got nothing to do with drones or cyber. It even has nothing to do with having a very rich ally (that is Lesson Learned #2).

The #1 Lesson Learned is this: nuclear deterrence works.

If you will, consider briefly how we got here.

On January 1st 1991, with the Soviet Union fragile, but still intact, the US had zero interest in Ukraine, essentially the same degree of interest the US had had in Ukraine since July 4th, 1776. On December 26th, 1991 that all changed. Ukraine was an independent nation (which would accord it some level of interest from every other nation), but more importantly, Ukraine had more than 1600 nuclear warheads (some counts go as high as 2,300 weapons). To give an idea of how large an arsenal that was, China, which is building between 70 and 100 nuclear weapons per year, will not have an arsenal that large until some time after 2030. Said differently, If Ukraine had simply refused to yield those weapons (which is another can of worms), it would today, more than 30 years later, still be the 3rd most powerful nuclear power - by quite a bit.

In any case, suddenly, the US had a very real interest in Ukraine simply because at that point Ukraine was the 3rd most powerful country in the world, or one might say the 3rd most potentially destructive country in the world. At the time, Russia had the largest nuclear arsenal in the world (about 35,000 weapons), and the US was number two (about 11,000). So, the issue was: would it be possible to eliminate all those Ukrainian weapons, ostensibly making the world a safer place?

How might Ukraine be given some incentive to give up its nuclear arsenal? To convince Ukraine to do this, President Clinton (and others - to include Russia and the UK) made promises to guarantee Ukrainian sovereignty.

At this point the State Department made certain to change the wording word from “Memorandum on security guarantees in connection with…” to “Memorandum on security assurances in connection with… ” This was done because a guarantee is, per the State Department, different than an assurance. A guarantee meant that the US would do something. An assurance, as one State Department veteran commented, meant that the US would talk about doing something.

Interestingly, the various texts are different:

The French version says: “garanties de sécurité”

The Russian version uses the word: гарантиях - which is Russian  for “guarantees.” 

The Ukrainian version uses the word: гарантіі - which is Ukrainian for “guarantees.”

But the US text is titled “…security assurances…” and for the US, it comes complete with the Foggy Bottom “nuance” encapsulated in that change from guarantee to assurance.

In 2014, when Russia seized Crimea and the US and Europe effectively did nothing, the message was sent to Russia that nothing meaningful was going to be done (it’s not accurate to say the US did nothing; some sanctions were levied against individuals; Moscow didn’t care.) 

It matters not at all whether Crimea was or was not ever part of Russia. Claims of 900 or 1000 or 1,100 year histories are no more relevant than a 1947 Chinese map found with a hand-drawn dashed line “proving” Chinese ownership of most of the South China Sea. Documents were signed in 1991 and again in 1994 that recognized the borders of Ukraine. Either those documents mean something or they do not. And what existed before was and is irrelevant. (The same applies to that asinine “nine dash line” drawn by hand across a map of the South China Sea.)

But, clearly, they didn't mean anything to Russia, and based on the international  response, they didn’t mean much to anyone else in 2014, outside of Ukraine. 7 years later, with Europe buying natural gas from Russia, and new pipelines under construction, it seemed to Russia that no one was going to object if they took some more. President Biden, fresh on the heels of the messy withdrawal from Kabul, commented that there might be a muted US response if Russia made just a “minor incursion.” Moscow, clearly   cognizant of US leadership miss-steps demonstrated in Kabul, decided the US had no real intent to confront Russia. So, Ukraine was a “gimme.”

Which leads to a simple question: If Ukraine had retained some of the nuclear weapons, if it needed no outside “security guarantee,” would Russia have attacked?

For that matter:

If Libya had kept their WMD program would we have attacked them in 2011? 

If Iran had finished their nuclear weapons, would we have attacked them earlier this year?

As DeGaulle said: “No country can call itself independent that does not have atomic weapons.”

Indeed… If North Korea did not have nuclear weapons might we have eventually decided to attack them?

And yet, at the same time, nuclear weapons have kept the Great Powers from engaging in open warfare. The threat of escalation, the fear of nuclear escalation, has kept great power confrontation inside certain limits. 

Consider what WWI and WWII taught us: How to kill on a grand scale. World-wide, war-related deaths averaged more than 25,000 per day for 6 years, perhaps as high as 35,000 per day, depending on what numbers you use. Other wars since 1945 have involved some truly horrific numbers of dead - the civil war in the Congo in particular, with perhaps 6 million dead. But the Great Powers have not squared off.

Which is why it is disconcerting to hear talk from folks who should know better about preparing to fight Russia conventionally in Europe… Western Europe was not kept out of Soviet hands because of NATO ground forces or NATO air forces. Those forces were a necessary but insufficient part of the solution. In the end, the USSR didn’t press westward because there were nuclear weapons on hand that would have landed on Soviet troops and inevitably on the Soviet Union. The result would have been killing and destruction on a truly grand scale, one that would make WWII deaths an afterthought.

A quick dive into the history of the French Nuclear Force, makes the point: DeGaulle pointed out to Gen. Gallois, the “father” of the French Nuclear Force, that it was not necessary to be able to destroy the USSR, but to simply be able to “tear off one arm.” The USSR would destroy France, but, as De Gaulle noted shortly after retuning to office in 1958:

“Within ten years, we shall have the means to kill 80 million Russians. I truly believe that one does not light-heartedly attack people who are able to kill 80 million Russians, even if one can kill 800 million French, that is if there were 800 million French.”

France’s population was just short of 50 million (68 million now). 

As Gallois later added:

"Making the most pessimistic assumptions, the French nuclear bombers could destroy ten Russian cities; and France is not a prize worthy of ten Russian cities.”

Simply put, the Soviet - now Russian - gain was not worth the loss irrespective of whatever else happened; that is the essence of nuclear deterrence. That there was, and is, a nuclear force independent from the US nuclear force, heightened the deterrence.

At the same time, the Grand Duchy of Fenwick not withstanding, nuclear deterrence is too high a risk if behind it there is not a robust conventional force that provides the ability to “dial up” and “dial down” the level of “tension.” As we found under President Carter, a national security budget of 4.5% was not adequate to engage in “full spectrum” deterrence. 

We can provide security guarantees to Ukraine, and to Taiwan and South Korea and Japan and the Philippines, but to do so will require both battlefield nuclear weapons and additional investments in non-nuclear forces. As Eisenhower noted, conventional forces alone, no matter how large, will not deter a great (a nuclear) power.

We need to remember all this as we look for a solution in Ukraine, and as we guarantee Taiwan and Japan and South Korea and our other allies in the Pacific.