The Illusion of Exit: Why the US can’t easily leave NATO and the consequences of 'strategic abandonment'

US President Donald Trump's frustration with European allies over their refusal to back Washington during the recent Iran crisis has triggered a crisis. Behind closed doors and on social media, Trump has openly questioned the alliance’s value, even suggesting the US might walk away.

The US-Iran war has exposed the NATO faultline like never before. US President Donald Trump's hostility towards allies is well known and that is one of the reasons that NATO nations refuse to back Trump blindly. This has irked the US President, as Trump is now officially considering pulling the United States out of NATO. The trigger, this time, is familiar—frustration with European allies who refused to back Washington during the recent Iran crisis. Behind closed doors and on social media, Trump has openly questioned the alliance’s value, even suggesting the US might walk away.

But here’s the part that gets lost in the noise: leaving NATO isn’t that simple. In fact, it’s almost designed not to be. An Indian-American Congressman, Raja Krishnamoorthi, has warned President Trump that any move to withdraw the United States from NATO without congressional approval would be illegal and would weaken national security. 

In a letter sent after Trump’s White House meeting with NATO Secretary General Mark Rutte, Congressman Raja Krishnamoorthi said, “Any unilateral US exit from NATO would be both strategically reckless and blatantly illegal under current law. Moreover, your rhetoric on this issue risks strengthening our adversaries at the expense of our own security."

The Legal Wall Trump Can’t Easily Cross

Since 2023, American law has made it clear—no president can unilaterally withdraw from NATO. Any such move would require either a two-thirds Senate vote or an act of Congress. That law wasn’t written in a vacuum. It was a direct response to growing concerns that a future president might try to dismantle the alliance on their own. Congress, in effect, locked the door.

Even today, lawmakers across party lines insist that a full withdrawal is unlikely to pass.

So, on paper, NATO is safe. But geopolitics rarely plays out on paper.

Real Strategy: Staying In, Pulling Back

If a clean exit is difficult, there’s another path—one that’s quieter, slower, and arguably more effective, feel analysts. Recent signals already point in that direction. The Pentagon has begun reducing participation in certain NATO programs, cutting personnel and scaling back involvement in key areas.

This includes reduced troop deployments in Europe, limited intelligence sharing, scaling down joint exercises and delaying or restrict military aid. None of this requires formally leaving NATO but it certainly threatens the alliance’s core strength.

This is what analysts call de facto disengagement—remaining a member in name, while hollowing out commitments in practice.

Why This Matters More Than a Formal Exit

A dramatic withdrawal would shock the world. But a slow retreat might be more damaging. NATO runs on one thing above all: trust. The belief that if one country is attacked, others—especially the United States—will show up. That’s Article 5, the alliance’s backbone. Undermine that belief, and the entire structure starts to wobble. And that’s already happening.

European allies, rattled by Washington’s rhetoric and recent tensions, are beginning to hedge. Defence spending is rising. Conversations about strategic autonomy—once theoretical—are becoming real.

Trump's second tenure has brought uncertainty for NATO, and their concern is not whether the US will leave the alliance or not. Their concern is whether NATO can sustain itself without the US or can it now rely on the US in times of need.

Slow Strategic Unravelling

Under Trump, the US has already been sending signals and if this continues, the fallout will be profound, if not immediate.

1. A Weaker Deterrent Against Russia

Without the full backing from America, NATO’s military credibility and capabilities drop sharply. The US accounts for the bulk of the alliance’s capability and funding. That creates openings—especially in Eastern Europe.

2. A More Independent, More Fragmented Europe

European nations have already begun investing more in their own defence. While this may sound comforting, this signals a greater risk - standing up to threats without the United States. If the US does a slow pullout, the transatlantic alliance could split into parallel power centres over time.

3. Loss of US Global Influence

NATO isn’t just a military pact—it’s a force multiplier. It gives Washington reach, bases, and legitimacy. Scaling back means giving that up, piece by piece.

4. A Boost for Rival Powers

Any visible fracture in NATO strengthens competitors like Russia and China. Not because they win a war—but because the West looks divided.

5. The Normalisation of Transactional Alliances

If NATO becomes conditional—support in exchange for cost-sharing or political alignment—it ceases to be an alliance in the traditional sense. It becomes a deal. And deals can be renegotiated or abandoned.

The Bigger Picture

Exit Without Leaving Trump hasn’t withdrawn from NATO. And legally, he may not be able to—at least not easily. But that may not matter because alliances don’t collapse only when treaties are signed or broken. Sometimes, they fade when commitments weaken, when trust erodes, when partners start planning for a future without each other.

That’s the real story here. The danger isn’t that the United States walks away from NATO overnight. It’s that it slowly stops showing up—and one day, the alliance realises it’s been standing alone for a while.