Too many times during his first, and particularly his second, administration, Donald Trump has threatened and bullied Europeans and the European alliance to spend more on defence “or else”. Given Trump’s unpredictability over what he may or may not do regarding the US presence in and support for NATO, there are a range of possible consequences arising from his quixotic and often whimsical actions for America’s longest-standing alliance – and questions about what NATO should do in response.

At this point, it is unknowable which, if any, US forces will be reduced or withdrawn from Europe. Possible changes to the command structure, including the nationality of the future Supreme Allied Commander Europe, are at least worrying. And the administration’s national security obsessions with preventing a Chinese invasion of Taiwan, however unlikely, and with homeland defence downplay, if not completely ignore, Europe and what many on the continent believe is a growing Russian threat, no matter how the war in Ukraine is resolved.

Whether Trump pulls forces from Romania, Poland, or Turkey or not – and, given his pique with Spain’s Prime Minister, he could remove US destroyers from their base in Rota – the US has already depleted its tactical aviation, naval, and air defence forces in Europe, deploying them to the Persian Gulf and Indian Ocean to fight in the war with Iran. NATO’s Supreme Allied Commander Europe (SACEUR), Air Force General Alexus Grynkewich, has already complained that his naval forces are insufficient to defend Israel from missile attack.

If one were a cynic, this is one way the Trump administration could be interpreting Article 5, the centrepiece and foundation of the alliance: “An attack on one shall be considered an attack against all”. “Shall be” is not “will be” or an absolute guarantee to respond. One should not dismiss this new reading of that solemn commitment as long as Trump is in power.

But let’s get to the main event: Trump’s National Security Strategy (NSS). These are the top three priorities, as quoted in the NSS. Note that the first two are interchangeable: “Defend the U.S. Homeland”; “Deter China in the Indo-Pacific Through Strength, Not Confrontation” with a “Sea Denial” strategy to prevent access to the First Island Chain (FIC); and “Increase Burden-Sharing with U.S. Allies and Partners.”

Defending the homeland, notwithstanding the military strikes on alleged drug-running boats in South American waters that should be the responsibility of law enforcement, means establishing a Golden Dome defence around the entire US, including Alaska, Hawaii, and overseas possessions. This was tried and failed under Ronald Reagan in the mid-1980s with the Strategic Defense Initiative, known as Star Wars.

The reasons were the infeasibility of properly defending against air-breathing, ballistic missile, and submarine threats, no matter how much was spent. While modern-day technologies have advanced dramatically, so too have their costs. The first consequence for Europe is that funds for Golden Dome must come from somewhere. That somewhere is conventional forces, meaning the US may have fewer available to come to the defence of NATO.

More critically, if Golden Dome works, will Russia attempt to recreate it? And, if so, what does that do to the nuclear deterrent value of French and UK forces and the scattering of US theatre nuclear weapons in Europe vis-à-vis Russia? The answer is not a good one.

But the near obsession with China is a more perplexing problem. US strategy is excessively focused on this unlikely contingency. President Barack Obama began this shift to the Pacific in 2011 with his “pivot” to Asia. Announced with little warning, it surprised and worried allies in Asia and Europe. China was angered. Trump has exacerbated this trend.

That has led to a downgrading of European defence as a priority and hence the thrust to impose strategic priority number three: requiring allies to spend more and accept a larger share of the defence burden. Increasing burden-sharing in Europe has been a goal since the alliance was founded in 1949. But threats are the wrong way to encourage more spending.

Worse, just because NATO members increase defence spending does not mean NATO’s overall military capability will be any greater. Indeed, a plan is needed to enhance overall NATO capability, much as “deep strike” was used 40 years ago. And there is a more sinister possibility.

Trump has downgraded the command structure in Europe, commensurate with the intention to reduce forces. Since General Dwight D. Eisenhower, the SACEUR has been an American. That has not only married the US to Europe; in the nuclear age, it has assured the link between the defence of Europe and the US strategic and tactical nuclear arsenals.

What can or should be done? In our forthcoming book, Who Thinks Best Wins: How Decisive Thinking Will Prevent Global Chaos, we argue that the single most important element in developing strategy is understanding what is required to win or succeed and what causes failure and defeat. Where has the alliance succeeded and why? And when or where has it faltered?

Success in the Cold War was very much a function of understanding the nature of the threat and the most effective means of countering it. The adoption of “deep strike” and “follow-on forces” attack exploited the Western military technological revolution. When the USSR collapsed and NATO lacked its raison d’être, “out of area or out of business” became the new foundation. Now, NATO needs a revitalised rationale. That can come from the war in Ukraine and from how a seemingly overwhelming Russian military power has been fought to a standstill.

Who Thinks Best Wins calls for a porcupine defence for NATO, meaning that any initial attack by Russia would be so obviously doomed to be repulsed, and so costly, that Moscow would not contemplate that option in the first instance. We lay out in detail how such a defence can be orchestrated in the Baltic and European centre and on the northern and Black Sea flanks without the need to increase defence spending to 3.5 percent.

NATO should take immediate action to implement this alliance-wide porcupine defence. Reflecting on NATO 3.0, the one place to take a stand is to demand that future SACEURs are American. While that cannot fully compensate for any major US force reductions, should they come, that position is the bond that will keep NATO whole, united, and allied.

The European Leadership Network itself as an institution holds no formal policy positions. The opinions articulated above represent the views of the authors rather than the European Leadership Network or its members. The ELN aims to encourage debates that will help develop Europe’s capacity to address the pressing foreign, defence, and security policy challenges of our time, to further its charitable purposes.

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