Donald Trump again threatened to pull the US from NATO.
What the latest threat says
President Donald J. Trump has renewed a warning that the United States might withdraw from the North Atlantic Treaty Organisation, citing allies' reluctance to support a US-Israel campaign against Iran. The statement came as part of a wider dispute over allied backing for US policy in the Middle East, and it has prompted fresh questions about whether such a move is doable and what it would mean for global security.
Al Jazeera correspondent Yasmeen ElTahan outlined the issue in a recent explainer. ElTahan noted that the president framed withdrawal as leverage over partners who he says won't back US action. That line of argument has been used before by Mr Trump in public remarks and campaigning; the current iteration ties the threat to a possible conflict with Iran.
So far the White House hasn't filed any formal paperwork to quit NATO, and there's no public record of a legal withdrawal process beginning. But the threat has sparked practical questions about how the treaty works and what the fallout would be, not just campaign talk.
How a US exit would work legally
The North Atlantic Treaty is a binding document among member states.
It also contains a procedure for a member to stop being a party to the treaty by giving notice. Under the treaty's terms, a state that wishes to leave must notify the depositary government — in practice, the United States is the depositary — and there's a waiting period before the withdrawal takes effect.
That means a decision to leave isn't instantaneous. It would require formal steps, and there would be time during which allies could press for a reversal or a rethink.
On paper the treaty spells out options, but in real life the politics would be messy and unpredictable.
The US has long provided the bulk of NATO's forces and nuclear deterrent, which many members still rely on. Any announced plan to depart would force capitals from Europe to Canada to weigh the credibility of US security guarantees and the practical consequences for defence planning.
Political shockwaves in Europe and beyond
An American withdrawal would be a major political event. European leaders would face immediate pressure to clarify defence plans and budgets. Some capitals could accelerate efforts to build EU-level or multinational defence arrangements; others would seek new bilateral guarantees from Washington. Either way, the alliance's coherence would be tested.
Allies that depend heavily on US intelligence, logistics and nuclear deterrence would have to reassess their strategic posture. That would also influence diplomacy with countries outside NATO, most obviously Russia and Iran, which would read an American pullback as altering the balance of power in Eurasia.
For NATO itself, the exit of its largest and most capable member would shake alliance institutions. Command structures, planning bodies and procurement projects have all been designed around US leadership and capacity. Members would need to rework budgets and force structures. That would be costly and time-consuming.
Economic and defence-industry impacts
Financial markets usually react badly to geopolitical shocks, so investors would probably take notice. An abrupt or credible threat to US participation in NATO would likely push investors to reassess geopolitical risk. Defence contractors in Europe and the US could see shifts in demand patterns. Projects co-funded by multiple NATO members might be delayed or cancelled if the alliance appears less stable.
Defence spending could rise in Europe as governments try to fill capability gaps. That means more public money channelled into procurement and personnel. Firms that supply equipment, from ships to missiles, could see order books change quickly. Energy markets and trade routes could also respond to shifting perceptions of stability in the Atlantic and Mediterranean.
None of that has to happen — a threat could fizzle, be reversed, or never translate into policy. Much would depend on whether a withdrawal was permanent, contested in domestic politics, or reversed after a short interval. Still, the economic ripple effects would be felt across industrial supply chains linked to defence, shipping, and risk-sensitive sectors like insurance and finance.
Implications for allies outside NATO
Countries that aren't NATO members but rely on US security policy would watch closely. Formal treaty ties differ, but the US presence underpins many global partnerships. A sudden shift in Washington's alliance commitments could complicate planning in the Indo-Pacific, where partners from Japan to Australia coordinate with the US on deterrence and force posture.
For Canberra, the main point is that US credibility as an ally matters beyond Europe. Australian defence planning is based on long-standing cooperation with the United States across intelligence sharing, exercises and matériel.
A decisive US move away from NATO wouldn't automatically change that relationship, but it would add uncertainty to long-term strategy and force posture discussions.
Domestic politics and the path to a decision
In the end, leaving NATO would be driven by US politics — the president could signal intent, but Congress and other actors would shape the final result. The White House can initiate a process, but sustained policy change of this magnitude usually encounters resistance in the political system and among allied capitals. Congressional opinion, public reaction and the views of US military leaders would shape the outcome.
Exit rhetoric has been a recurring feature of internal debate over burden-sharing within NATO. Some US politicians and voters have long criticised allied defence spending levels. That argument has at times been used to press NATO members to raise their contributions. Turning that argument into an actual withdrawal would be a far larger step — and one with far-reaching costs.
Diplomats, military planners and investors would all be watching closely if the US seriously pursued a NATO exit. It also matters to voters across NATO countries whose governments would face immediate policy choices if Washington moved to leave.
What comes next
The immediate reaction from most capitals is likely to be caution.
Allies will try to gauge whether the threat is a negotiating tactic or the prelude to real action. Some will press privately; others will respond publicly with statements of concern.
On the US side, the pace of any legal action, and whether Congress gets more involved, will be key. The treaty mechanism gives time for back-and-forth. Whether that time will be used for diplomacy or for escalating confrontation is an open question.
Yasmeen ElTahan's explainer put the matter bluntly: the president can use the threat as leverage, but actually disentangling the US from NATO would be a complex, costly and politically fraught undertaking. Allies have experienced presidents who make blunt statements.
They have also dealt with presidents who follow through on major policy shifts. Which path unfolds now will shape alliance politics for years.
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Under Article 13 of the North Atlantic Treaty, a member state can cease to be a party one year after giving notice to the depositary government.
This article was created with AI assistance.
