Eighty Years of Borrowed Security: What It Takes for Europe to Defend Itself After Decades Under the American Umbrella, and What It Costs

The security arrangement began in 1949 amid the wreckage of the Second World War. On April 4 of that year, twelve countries, including the United States, Britain, France, Canada, and several Western European nations, signed the North Atlantic Treaty in Washington. The brief document contains only 14 articles. At its core is Article 5, which pledges that an armed attack against one member in Europe or North America is an attack against them all. The primary purpose at the time was to deter the Soviet Union, which had established the Iron Curtain across Eastern Europe and stationed large armies there.

During the four decades of the Cold War, the United States anchored this deterrence. Washington stationed troops across Western Europe, provided the alliance's top commander, and backed the security guarantee with its nuclear arsenal. While Europeans contributed forces and bases, the United States carried the largest share of the cost and risk. This defensive shield allowed Western European governments to fund expansive health, pension, and welfare systems during the postwar decades.

The only time the mutual defense clause was formally invoked, it functioned in the opposite direction of what its founders envisioned. On September 12, 2001, the day after the terrorist attacks on New York and Washington, NATO allies invoked Article 5 for the first time on behalf of the United States. European and Canadian forces joined the response, and NATO aircraft even helped patrol American skies, marking a historic moment where Europe came to the defense of the United States.

Complaints that Europe spent too little on its own defense are not new. At a September 2014 summit in Wales, months after Russia annexed Crimea, NATO members agreed to spend at least 2 percent of their gross domestic product on defense within a decade. At the time, only three allies met this threshold, and most members missed the target for years. Successive American presidents, including Barack Obama and Donald Trump during his first term, consistently pressed European allies to increase their contributions.

The debate shifted dramatically on February 24, 2022, when Russia launched a full-scale invasion of Ukraine, initiating the largest land war in Europe since 1945. Three days later, German Chancellor Olaf Scholz declared a "Zeitenwende," or historical turning point, before parliament. He announced a borrowed, 100-billion-euro special fund to rebuild Germany's long-neglected military and pledged to push defense spending above 2 percent of national income. For Germany, which had kept its military deliberately modest since 1945, this marked a historic break.

Other governments made similar moves, some even earlier. Poland, which borders both Ukraine and Belarus, raised its defense budget to the highest level in the alliance relative to its economy. According to the Stockholm International Peace Research Institute (SIPRI), Poland spent roughly 4.5 percent of its GDP on defense by 2025, outspending every other NATO member. The Polish government also drafted a 2026 budget aiming for nearly 4.8 percent.

The European Union, which overlaps heavily with NATO membership, provided its own initiative. On March 4, 2025, European Commission President Ursula von der Leyen unveiled "ReArm Europe," a plan later branded "Readiness 2030" that aims to mobilize up to 800 billion euros for defense. The largest portion, worth nearly 650 billion euros over four years, involves loosening EU budget rules to allow member states to borrow and spend on their militaries without penalty. The remaining 150 billion euros comes from a joint borrowing instrument called Security Action for Europe (SAFE), adopted on May 27, 2025, to fund collaborative weapons purchases.

The most significant decision occurred in June 2025 during a NATO summit in The Hague, where allies agreed to raise their spending target to 5 percent of GDP by 2035. This new target is split into two components: at least 3.5 percent for core military spending, such as troops and weapons, and up to 1.5 percent for broader security needs, including critical infrastructure and cyber defense. Progress will be reviewed in 2029. Spain emerged as a public exception when Prime Minister Pedro Sanchez claimed he secured flexibility to spend roughly 2.1 percent, though NATO Secretary General Mark Rutte insisted that no formal exemptions exist and all allies are expected to meet the target.

This urgency was driven by a sharp strategic shift in Washington. In February 2025, U.S. Defense Secretary Pete Hegseth informed European allies that the United States would no longer focus primarily on European security, urging them to take ownership of conventional defense while America pivots toward challenges in Asia. The Trump administration subsequently began reducing the U.S. presence in Europe from its early 2025 level of roughly 84,000 troops. The Pentagon withdrew several thousand personnel and canceled planned deployments to Poland and Romania, drawing concern from European governments and rare public pushback from congressional Republicans.

These financial figures underscore the scale of this shift. In April 2026, SIPRI reported that European military spending surged 14 percent in 2025 to a record 864 billion dollars, marking the fastest annual increase for European allies since 1953. Germany became the group's largest spender, increasing its outlay by 24 percent to 114 billion dollars and exceeding 2 percent of its GDP for the first time since 1990. Meanwhile, U.S. military spending decreased by 7.5 percent to 954 billion dollars, largely because Washington approved no new military aid for Ukraine in 2025. During the same period, Russia spent roughly 190 billion dollars, or 7.5 percent of its economy, while Ukraine spent 84 billion dollars, representing about 40 percent of its economy. The July 2026 summit in Ankara, Turkey, will measure how far these spending commitments have progressed toward reality.

1. Atlanticists who want to keep NATO and the American guarantee central

   i. The American umbrella is proven, and nothing Europe can build soon will match it.

   Supporters of keeping the United States at the center of European defense rely on historical success rather than theory. For more than seven decades, the American guarantee successfully deterred a Soviet, and later Russian, attack on NATO territory without a single Article 5 war in Europe. The United States supplies critical capabilities that no European state possesses at scale, including the bulk of the alliance's nuclear deterrent, extensive satellite and intelligence reach, heavy airlift, and the command structure that unites thirty-two militaries. NATO Secretary General Mark Rutte and most allied governments argue that walking away from this established shield in favor of an unfinished one would undermine regional security.

   ii. Unity is itself the deterrent, and a divided West invites a test.

   Atlanticists argue that Moscow is deterred by collective credibility, not by any single weapon system. If the belief remains intact that an attack on one ally involves all members, including the United States, deterrence holds. If that consensus fractures, an adversary may gamble that the alliance will not fight. Consequently, even staunch advocates of higher European spending, including leaders in Poland and the Baltic states, frame their buildup as strengthening NATO from within. Their objective is to maintain the American commitment by proving Europe carries its weight, rather than pushing the United States out.

2. Advocates of European strategic autonomy

   i. Europe cannot bet its survival on the reliability of foreign election cycles.

   Supporters of European strategic autonomy, the concept that Europe should defend itself without depending on the United States, point to Washington's actions in 2025. U.S. Defense Secretary Pete Hegseth stated in February 2025 that America could no longer focus primarily on European security, a message reinforced by the subsequent drawdown of Pentagon forces. Autonomy advocates view these developments as a clear warning that the American guarantee is no longer guaranteed. French President Emmanuel Macron has long argued that Europe must become a military power in its own right, asserting that a continent with a population exceeding 400 million and an economy far larger than Russia's should not rely on decisions made in another capital.

   ii. The capability gap is closing, and the funding is real.

   Autonomy advocates argue that self-reliance is now an achievable goal rather than a slogan. The European Union's "ReArm Europe" plan aims to mobilize up to 800 billion euros, supported by the 150 billion euro SAFE loan tool adopted in May 2025 for joint weapons procurement and defense industry revitalization. Proponents cite Germany's 100 billion euro special fund and Poland's 2025 defense spending of roughly 4.5 percent of its GDP as evidence that Europe can finance serious military forces. Furthermore, SIPRI reported a 14 percent surge in European spending in 2025 to a record 864 billion dollars, proving the transition from rhetoric to hardware has begun.

3. The United States view

   i. Burden-sharing is long overdue after years of unfulfilled promises.

   The American perspective, maintained across multiple administrations and sharpened under President Trump, holds that the lopsided defense burden was meant to be temporary but became an unbroken habit. The United States notes that while allies pledged in 2014 to reach a 2 percent GDP spending target, only three met it that year, leaving American taxpayers to fill the gap for the next decade. Washington argues it has long subsidized the defense of wealthy democracies capable of paying their own way. From this viewpoint, the 5 percent target agreed upon in June 2025 simply requires Europe to fund the security it expects.

   ii. The United States faces a real strategic choice and cannot manage every theater simultaneously.

   American officials maintain that the strategic pivot is driven by necessity. Defense Secretary Hegseth informed allies in February 2025 that stark strategic realities force the United States to prioritize its resources. Washington views China and the Asian theater as its most serious long-term challenges. The administration's position is that the United States cannot remain the primary guarantor of European land defense while simultaneously preparing for potential conflict in the Pacific. Asking Europe to take ownership of its conventional security frees American assets for the theater Washington deems most critical, while still keeping the United States engaged in NATO.

1. Critics of the Atlanticists who want to keep the guarantee central

   i. Leaning on a guarantee that Washington openly questions is a dangerous strategy.

   Critics, including many autonomy advocates, argue that the Atlanticist position relies on a promise the United States is actively hedging. With American leaders publicly stating that Europe is no longer their primary security concern and subsequently drawing down forces, planning around full American protection risks leaving Europe exposed. Furthermore, remaining under the U.S. umbrella has already caused decades of European underinvestment, proving that relying on Washington's shifting political priorities is an unsafe strategy for the continent.

   ii. The current structure concentrates too much capability in one nation's hands.

   A second criticism is that decades of overreliance on the United States left Europe without critical capabilities it should have developed independently. These deficiencies range from satellite intelligence and heavy airlift to a coordinated nuclear posture. By the time of Russia's 2022 invasion of Ukraine, several European militaries possessed thin ammunition stockpiles and limited capacity to sustain a prolonged conflict without American logistics. Critics argue this dependency is the direct result of Atlanticist complacency, where treating NATO unity as a substitute for true European capacity has left the continent fragile.

2. Critics of the advocates of European strategic autonomy

   i. The economic and political costs of rearming will heavily strain welfare budgets.

   The sharpest objection to the autonomy push is the financial bill. Reaching the 3.5 percent GDP target for core military spending requires tens of billions of euros annually, and the broader 5 percent security target demands even more. Spanish Prime Minister Pedro Sanchez made this case in June 2025, calling the 5 percent target disproportionate and incompatible with funding a modern welfare state, noting Spain would aim for roughly 2.1 percent. Critics warn that diverting funds to defense will inevitably squeeze pensions, healthcare, and social spending at a time when Europe faces aging populations and strained public finances, potentially triggering voter revolts.

   ii. Fragmented and duplicated forces mean European spending buys less capability.

   Critics also point out that European defense spending is highly inefficient because funds are split across separate national armies that purchase incompatible equipment. Analysts note that Europe operates significantly more types of weapons systems than the United States, driven by national industries protecting local jobs and contracts. Without deep joint procurement and standardization, a large share of the new 800 billion euro initiative could be wasted on duplication, leaving Europe with less combat power than the headline figures suggest. Building genuine autonomy requires a level of political integration that member states have long resisted.

3. Critics of the United States view

   i. Pulling back risks undermining the deterrence and credibility Washington built.

   Critics of the American approach, including several congressional Republicans, argue that questioning the guarantee and reducing troop numbers weakens collective deterrence. The Pentagon's 2025 decision to draw down the 84,000 U.S. troops in Europe and cancel planned deployments drew warnings from lawmakers and European governments, who argued it signaled weakness to Moscow during an active land war. Critics emphasize that American credibility is a vital strategic asset, and casting public doubt on an alliance the U.S. spent generations building serves as a gift to adversaries.

   ii. Transactional demands risk alienating allies and fracturing the Western alliance.**

   Further criticism suggests that blunt pressure from Washington could backfire by forcing Europe to plan for a future without the United States. If allies conclude the American guarantee is conditional and unreliable, they will likely develop separate European military structures that could eventually erode the alliance Washington still wishes to lead. Treating long-standing democratic allies as freeloaders strains the core trust of NATO, meaning the United States risks bargaining away strategic influence it spent decades accumulating.