Europe Is Ready to Shelter Under France’s Nuclear Umbrella

“Alarmed by Trump, Poland Must Look at Nuclear Options, Premier Says”

“Poland must look at acquiring nuclear weapons, says Donald Tusk”

“Poland seeks access to nuclear arms and looks to build half-million-man army”

Scanning the headlines, you’d be forgiven for thinking that Poland was about to go nuclear. If we know one thing about the nuclear age, it is that it is far easier to talk about building the bomb than it is to actually make one.

What Donald Tusk, the prime minister of Poland, raised in early March was the possibility of France extending nuclear deterrence to Poland, not Warsaw making plutonium-filled pierogis. At least, for the moment.

Tusk’s speech was a 47 minute stem-winder to the Sejm, Poland’s lower house of Parliament. You can watch it online (with auto-translated captions, if you don’t speak Polish).

If Warsaw was planning on going nuclear, then that would have been the primary focus. It wasn’t. Instead, the speech was largely about the international situation, the need to support Ukraine, and several proposals for increasing Poland’s defense capabilities.

In the course of that long speech, Tusk touched on the topic of nuclear weapons only twice, both times in passing at the tail end of the speech. The key remark was this:

“And we also need to look more boldly into the future in terms of weapons technology. We are talking seriously with the French about their idea of ​​a nuclear umbrella over Europe. It is high time for Poland to use the means it has, as well as its own experience, but also experience on the battlefield.”

But while that plan might be less dramatic than developing nukes in Warsaw, the growing interest in France—the European Union’s only nuclear power post-Brexit—extending nuclear deterrence to NATO allies is really quite remarkable.

Since 2020, French President Emmanuel Macron has hinted at the idea of extending nuclear deterrence to France’s European allies, but only implicitly. Macron has also repeatedly referred to the “European dimension” of France’s vital interests, leaving the rest to the listener’s imagination.

When he said it again in January, Macron was misquoted as having said the quiet part out loud. His opponents on the left and right pounced on him. But then Friedrich Merz—the leader of Germany’s Christian Democratic Union and now the presumptive next chancellor—said in late February that Germany should “have discussions with both the British and the French—the two European nuclear powers—about whether nuclear sharing, or at least nuclear security from the U.K. and France, could also apply to us.”

A few days after that, Tusk, as well the leaders of all three Baltic republics, also expressed interest in Macron’s suggestions.

That NATO nations are discussing whether and how France might extend deterrence is a sign of how sharply the European security environment has changed.

For the entirety of the North Atlantic alliance’s history, NATO’s nuclear deterrence has come from the United States. True, the United Kingdom has a small force of nuclear weapons. But it is the United States that forward-deploys nuclear weapons in several NATO countries.

France, which tested its first nuclear weapon in 1960, has always remained apart from these activities. France does not participate in NATO’s nuclear planning group or its high-level group.

What has changed, of course, is U.S. President Donald Trump. European leaders are increasingly wondering if a single nuclear umbrella is enough.

It’s an odd term. An umbrella keeps the rain off you—it doesn’t blow up the clouds. But extended nuclear deterrence is, at its core, a threat to retaliate.

Deterrence is also in the eye of the beholder. There is no explicit legal agreement by the United States to respond to nuclear weapons in a specific way, or to use nuclear weapons in specific situations.

The United States has a general obligation to Poland and other NATO members to respond to an armed attack on any member. The United States also has 3,748 nuclear weapons at last count, in September 2023. At some level, France and the United Kingdom are no different. They have the same general obligation—and, of course, they also possess (fewer) nuclear weapons.

But France and the U.K. do not extend nuclear deterrence in the same way the United States does. The challenge of extending a nuclear “umbrella” is making sure that the threat to respond to an armed attack on them with our weapons is credible in scenarios where nuclear weapons come into play.

The implicit nature of the task is why we defense wonks favor weird circumlocutions such as the “nuclear character” of the alliance. Giving the alliance a touch of nuclear deterrence is why the United States forward-deploys nuclear weapons in member nations for allied use. It is also why the United States, at least before Trump, talked about the importance of consultation through the nuclear planning group as well as burden-sharing in the form of allied aircraft capable of delivering those nuclear weapons.

France, by contrast, has been outside these arrangements. What Macron, Merz, Tusk, and others are exploring is whether NATO might become a nuclear potluck, with escargot to complement the hot dogs.

The details, of course, matter a tremendous deal. France might just give Poland a security guarantee. Or France could invite Polish fighters to practice escorting French nuclear-armed strike aircraft en route to Moscow, something that Poland already does with the United States (through the Support of Nuclear Operations With Conventional Air Tactics program, or SNOWCAT). Or France could station some of those fighters in Poland.

Or, yes, France could devise arrangements for nuclear sharing. Poland is codeveloping a long-range cruise missile with France, Germany, and Italy. Perhaps France will make available nuclear warheads for Poland in extremis, just as the United States plans to make available nuclear gravity bombs for select NATO allies.

But there is an enormous difference between Macron stating that Poland’s sovereignty is a French vital interest and actually shipping a stockpile of nuclear armed-cruise missiles to Gdansk. At the moment, this is all just a conversation.

If Poland, on the other hand, actually wanted its own independent nuclear weapons, that’s another story entirely. It’s easy to talk about building a nuclear arsenal, but it’s rather another thing to do it. One of the things that is common knowledge in the nuclear field, but actually kind of surprising to normal people, is that designing a compact weapon is actually pretty easy.

Thermonuclear weapons designs haven’t changed a lot in the past 50 years. What is difficult, on the other hand, is building the facilities to produce the nuclear material—plutonium or highly enriched uranium—that is the heart of a nuclear explosive.

It’s also straightforward to import uranium ore, but the explodey sort of uranium—the fissile isotope U-235—makes up less than 1 percent of the uranium found in the ground. That’s where a would-be nuclear power needs to start building relatively large industrial enterprises.

If Poland intended to develop its own nuclear arsenal, then it would have two options. First, it could build a conversion facility to treat uranium with fluoride to turn it into a gas and then feed that gas into a large plant filled with centrifuges to enrich the uranium to weapons grade before converting the gas back into metal.

This is the route that Iran seems to have taken since the early 2000s, although Tehran started with a fair amount of help from the now-defunct network operated by Pakistani scientist A.Q. Khan.

Second, Poland could build a nuclear reactor and fill it with uranium metal fuel rods. Over a couple of years, the chain reaction within the reactor will turn some of the uranium metal in the fuel rods into plutonium, which makes for a very nice nuclear weapon indeed.

But that plutonium is trapped in spent fuel—highly radioactive nuclear waste. So Poland would also have to build a large chemical reprocessing facility to chop up the spent fuel, dissolve it in acid, and chemically separate the plutonium metal, which could then be fashioned into a bomb.

These are large and expensive industrial enterprises. When the Danish physicist Niels Bohr received a briefing on the U.S. Manhattan Project, he turned to fellow physicist Edward Teller and said: “You see, I told you it couldn’t be done without turning the whole country into a factory. You have done just that.” Maybe Bohr was thinking of a Denmark-sized factory-country, but still.

In October 2022, Poland announced that it had selected Westinghouse to build three civilian nuclear power reactors for about $20 billion each. Construction is expected to start in 2026 and will take about seven years. These reactors will make plutonium, but they will be under international safeguards, and their design makes it much more difficult to use the plutonium in a weapon. (The same goes for Poland’s MARIA research reactor.)

Still, the timeline gives some idea of how long it would take Poland to build the facilities necessary. Poland would also have to think about how to deliver such a weapon, which means making decisions about missiles or fighter aircraft. Nuclear weapons programs are measured in years, sometimes decades, with expenses running in the many tens of billions of dollars.

The need to build expensive industrial projects that take a long time is, in large part, why many leaders have found talk easier than action when it comes to the bomb. As my colleague at the Middlebury Institute, Philipp Bleek, has argued, many countries—including U.S. allies—have explored a nuclear weapons option in one fashion or another. Algeria, Argentina, Australia, Brazil, Egypt, (West) Germany, Indonesia, Iraq, Italy, Japan, Libya, Norway, Romania, South Korea, Sweden, Switzerland, Syria, and Taiwan have all at least considered the possibility of a nuclear-armed future.

Very few countries that have explored have followed through, and currently, only nine countries have gone all the way and acquired them. Iran is somewhere in between, although that story is not yet over. Tehran would make 10.

That’s because producing nuclear material is expensive, difficult, and takes a long time. Obviously, Poland could go faster with help. But historically, long timelines have afforded the United States both leverage over potential proliferators, who also needed help to get their program going, and time to make them a better offer—or at least an offer that they can’t refuse.

For allies, time allows the United States to offer immediate and attractive options, such as extended nuclear deterrence, in place of an uncertain and very prospective pursuit of independent nuclear deterrent. In Europe and Asia, for example, U.S. offers of nuclear-sharing and forward deployment helped dissuade nuclear-capable allies such as Germany and Japan from acquiring their own weapons. The gift of time also means that determined leaders might not be around long enough to follow through, or that the circumstances that make nuclear weapons appealing might change.

That’s worth keeping in mind, because Poland’s current interest in nuclear weapons has a lot to do with a very specific 78-year-old leader. During his first term, Trump openly mused about other countries building their own nuclear weapons if they weren’t willing to pay the United States more for security. Those statements seem to have been more about calling what Trump saw as a bluff to avoid coughing up more money rather than an actual policy preference.

But for some Trump administration defense officials, allied proliferation is a policy preference. It is not surprising, in these circumstances, that Tusk and others would consider their options. But building a bomb takes time. Will the shadow of Trump stretch out to the decade or so that it might take Poland to fashion an independent deterrent?

Perhaps it will. Tusk did not rule out an independent Polish nuclear deterrent in the future and, if things continue the way they have been, many more countries may be weighing their options.

Whether that future comes to pass will depend tremendously on the ability of the United States—and now France—to address Polish security concerns in this new, more dangerous environment.