The war in Ukraine shows that nuclear deterrence works

During the first Cold War, Nato’s main security concern was the overwhelming superiority in conventional military forces enjoyed by the Soviet Union and the Warsaw Pact nations. There was a real fear that they might be tempted to use that power to launch a surprise attack, which might overwhelm Nato's defences and rapidly enable them to reach the English Channel.

Over the years, a variety of strategies were developed for dealing with the problem: massive retaliation, tripwire and flexible response were the best known. The strategies were all based on the threat of using nuclear weapons. The idea that the possession of nuclear weapons was a means of preventing a militarily more powerful opponent from doing what he might otherwise be tempted to do was central to Nato’s thinking. French academics rationalised this, in the context of France's own national deterrent, into the notion of “dissuasion du faible au fort” (deterrence of the strong by the weak).

This is what is happening now in the war between Russia and Ukraine, except it is Nato which is being deterred. Russia has powerful conventional armed forces, but they do not dominate Europe in the way that those of the Soviet Union once did. In order to find the critical mass necessary to invade Ukraine, Russia has had to move units from elsewhere in its territory—to the point where parts of its international frontiers are now only lightly guarded. Even so, it has still not succeeded in winning the war.

Had Russia not been a nuclear power, Nato would have had a wider range of options for supporting Ukraine. They would have included the supply of weaponry, such as long-range artillery, strike aircraft or cruise missiles, capable of interdicting logistic facilities or other targets on Russian territory; the imposition of a naval blockade on Russian ports in the Black Sea; or even the direct involvement in the war of Nato ground or air forces. All this would have been compliant with international law, given Ukraine’s right under Article 51 of the UN Charter to seek assistance in defending itself against attack. (Whether it would have been politically wise is another question.)

But Russia is the biggest nuclear power in the world and has not been reticent in drawing attention to this fact. It has implied a willingness to use its nuclear weapons to defend its vital national interests, albeit without specifying exactly what these interests are. On Monday, Dmitry Kiselyov, a presenter known as “Vladimir Putin’s mouthpiece,” showed a video on Russian state TV of an underwater missile simulating an attack on Ireland and the UK. In deciding how far to go in providing military support to Ukraine, Nato has been rightly concerned not to do anything which might provoke a nuclear response. Russia’s possession of nuclear weapons has clearly been a strategic asset in its war on Ukraine. This was not the case in the Vietnam or Falkland wars as the North Vietnamese and the Argentinians calculated, correctly, that the US and the UK would not be prepared to use nuclear weapons in circumstances where their own vital national security was not at stake.

When the Soviet Union collapsed, Ukraine had significant numbers of both tactical and strategic nuclear weapons on its territory. The SS24 ICBM was designed and built in Ukraine. In 1994, Ukraine gave up all its missiles and warheads and, under the terms of the Budapest Agreement, acceded to the Non-Proliferation Treaty as a non-nuclear state in return for guarantees from Russia, the UK and the US to respect its sovereignty and territorial integrity. It would have been technically difficult for Ukraine to exercise operational control over the weapons: the Permissive Action Links (ie the release codes) were in Russian hands. But with the benefit of hindsight this was, from Ukraine's point of view, a mistake. The co-signatories of the agreement have not been able—or in the case of Russia, willing—to honour their commitment.

Other countries too may draw conclusions from the way that Russia's possession of nuclear weapons, and its impact on Nato's decision-making, has affected the war in Ukraine. North Korea will feel justified in pursuing its own nuclear weapons programme. So too, probably, will Iran, although it may, like Israel, not publicly acknowledge that it is doing so. The chances of reviving the Iran nuclear deal now look even slimmer. In the longer run, South Korea and Japan may review their options. Both have the domestic capability for developing their own nuclear weapons programmes and both feel threatened by North Korea and China. Hitherto the Japanese people’s revulsion against nuclear weapons as a result of their own experiences at Hiroshima and Nagasaki has inhibited any potential move by a Japanese government in this direction. Whether this will always apply in the future is less clear.

For decades following the first nuclear explosion at Los Alamos in 1945, nuclear weapons were seen by many strategists as a means, even if not an ideal one, of assuring peace and security in an antagonistic world. The genie cannot be put back in the bottle. But no one could seriously claim today that the world would not be a safer place without them.