The security landscape of the Western world faces its gravest challenge since the end of World War II, and this shift is likely to be long-term. As one expert notes, “Trumpism will outlast his presidency.” With the U.S. taking a step back, the pressing question is which nations are prepared to assume a leadership role.
In February 1947, at 9:00 AM, Lord Inverchapel, the British ambassador to Washington, entered the U.S. State Department with two critical diplomatic messages printed on blue paper—one concerning Greece and the other Turkey. Britain, financially drained and deeply indebted to the U.S., declared it could no longer support Greek government forces battling a Communist insurgency. Simultaneously, Britain was withdrawing from Palestine and India and reducing its presence in Egypt.
Recognizing the threat of Soviet influence expanding into Greece and potentially Turkey, the U.S. swiftly responded. President Harry Truman proclaimed, “It must be a policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressure.” This policy, known as the Truman Doctrine, cemented the idea that defending democracy abroad aligned with U.S. national interests.
Following this shift, the U.S. launched the Marshall Plan to rebuild European economies and helped establish NATO in 1949 to counter Soviet expansion. This period marked the definitive transfer of Western leadership from Britain to the United States. With its vast economic and military power, the U.S. emerged as the dominant force shaping the post-war world.
For decades, the U.S. played a central role in maintaining global security, but now, the fundamental assumptions behind its foreign policy are being questioned. Donald Trump is the first post-World War II president to challenge America’s global commitments. His stance has created uncertainty about the existing world order and left many wondering what the new one will look like.
A Challenge to the Truman Legacy
Trump’s skepticism of America’s international obligations is not new. Nearly 40 years ago, he placed full-page ads in U.S. newspapers criticizing the country’s military commitments. In 1987, he wrote, “For decades, Japan and other nations have been taking advantage of the United States. Why are these nations not paying the United States for the human lives and billions of dollars we are losing to protect their interests? The world is laughing at America’s politicians as we protect ships we don’t own, carrying oil we don’t need, destined for allies who won’t help.”
This sentiment has persisted into his second term. Recently leaked messages on airstrikes against Yemen’s Houthis revealed administration officials expressing frustration over European reliance on U.S. military action. A message attributed to Vice President J.D. Vance read, “I just hate bailing Europe out again.” In response, another, reportedly from Defense Secretary Pete Hegseth, stated, “VP: I fully share your loathing of European free-loading. It’s PATHETIC.”
Trump has gone further by embracing Russian President Vladimir Putin. Early in his second term, he informed Russia that Ukraine would not be allowed NATO membership and that he did not expect Ukraine to regain lost territories. Many critics saw this as a strategic blunder, surrendering leverage without securing anything in return.
Some Trump supporters view Putin as an ally in the ideological battle against liberal values, reinforcing the notion that U.S. foreign policy is increasingly shaped by domestic culture wars. Ed Arnold, a senior research fellow at the Royal United Services Institute, warns, “The US is becoming divorced from European values. That’s difficult [for Europeans] to swallow because it means that it’s structural, cultural, and potentially long-term. I think the current trajectory of the US will outlast Trump, as a person. I think Trumpism will outlast his presidency.”
NATO’s Article 5 “On Life Support”
Trump’s administration has signaled that the U.S. will no longer be the primary guarantor of European security, insisting that European nations must take responsibility for their own defense. Earlier this month, Trump stated, “If [NATO countries] don’t pay, I’m not going to defend them. No, I’m not going to defend them.”
For nearly 80 years, NATO’s Article 5—stating that an attack on one member is an attack on all—has been the bedrock of European security. While UK Prime Minister Sir Keir Starmer expressed confidence in the U.S. commitment to NATO, others remain skeptical.
Ben Wallace, former UK defense secretary, warned, “I think Article 5 is on life support. If Europe, including the United Kingdom, doesn’t step up to the plate, invest a lot on defense, and take it seriously, it’s potentially the end of the NATO that we know and it’ll be the end of Article 5. Right now, I wouldn’t bet my house that Article 5 would be able to be triggered in the event of a Russian attack… I certainly wouldn’t take for granted that the United States would ride to the rescue.”
Public perception reflects this shift. A French poll by Institut Elabe found that nearly three-quarters of respondents do not consider the U.S. an ally of France. Majorities in traditionally pro-American nations like the UK and Denmark also hold unfavorable views of the U.S. Robert Kagan, a senior fellow at the Brookings Institute, argues, “The damage Trump has done to NATO is probably irreparable. The alliance relied on an American guarantee that is no longer reliable, to say the least.”
Is the West Fragmenting?
For Russian President Putin, these developments play into his strategy of destabilizing Europe. After Ukrainian President Volodymyr Zelensky’s unsuccessful meeting with Trump, a Kremlin spokesperson declared, “The fragmentation of the West has begun.”
Armida van Rij of Chatham House echoes this concern: “Russia’s objectives are to destabilize Europe. It is to weaken NATO and get the Americans to withdraw their troops from here. And at the moment, you could go ‘tick, tick, and almost tick.'”
Meanwhile, European defense spending has dwindled. The UK, for example, has cut its military budget by nearly 70% since the Cold War peak. Wallace laments, “We had a big budget [during the Cold War] and we took a peace dividend… The problem is we went from a peace dividend to corporate raiding. [Defense] just became the go-to department to take money from. And that is where we just forgot the lessons of our history.”
Germany’s Chancellor-in-waiting, Friedrich Merz, has called for a Europe independent of the U.S. But building an autonomous European military-industrial complex remains a complex challenge. Ian Bond of the Centre for European Reform notes, “The further west you go, the more problematic it becomes until you get to Spain and Italy.”
A New World Order?
Historian Timothy Garton Ash identifies key military assets that only the U.S. currently provides: “The satellites, the intelligence, the Patriot air defense batteries, which are the only ones that can take down Russian ballistic missiles.” He argues that within five years, Europe should develop its own capabilities to replace U.S. support.
Van Rij acknowledges that while European defense autonomy is necessary, “what’s really difficult are the divisions within Europe on how to actually do this and whether to actually do this.”
Trump’s vision appears to favor a world where major powers dictate terms to weaker nations, akin to the spheres of influence system of the Cold War era. The uncertainty surrounding U.S. commitments has left Europe facing a pivotal decision: unite, invest in defense, and maintain independence—or risk becoming subordinate to larger global powers.