Defense Secretary Pete Hegseth called for a fundamental restructuring of the NATO alliance during an address in Brussels on Friday, arguing that European members must take primary responsibility for their own defense while the United States refocuses its military resources toward the Indo-Pacific.

Hegseth used the phrase “NATO 3.0” repeatedly during his speech at NATO headquarters, describing the first phase as the Cold War alliance and the second as the post-September 11 expansion. He argued the current moment required a third evolution in which European nations meet or exceed the two percent GDP defense spending target without relying on US forces as their primary backstop.

He announced simultaneously that the Pentagon had opened a formal review of US military posture in Europe, examining troop levels, basing arrangements, and command structures across the continent. The review was ordered by President Trump and is expected to take 90 days. Officials declined to say what options were on the table, but did not rule out reductions in the current 80,000-plus US troops stationed across European NATO countries.

The speech prompted immediate concern from several European NATO members. Germany’s defense minister said Berlin “would not assume” the review would lead to withdrawal and urged Washington to consult allies before making any decisions. Poland, which has the largest per capita US military presence of any NATO member, said through a spokesman that it hoped the review would affirm rather than reduce the American commitment.

Hegseth pushed back on that framing, saying the United States remained committed to NATO’s Article 5 mutual defense provisions but arguing that commitment did not require the current force structure. He said Europe had for too long taken American presence for granted and that a leaner arrangement could actually be more strategically durable.

The speech came four months after the Trump administration imposed a 60-day deadline on European NATO allies to submit plans to reach two percent GDP spending by the end of 2027. Several countries including France, Germany, and the UK have since announced accelerated defense budgets, but the continent as a whole remains below the target. NATO Secretary General Mark Rutte met with Hegseth privately before the speech.

The posture review adds another variable to a European security environment already unsettled by the ongoing war in Ukraine, which is now in its fifth year. US military aid to Ukraine has continued under the Trump administration, though at a reduced pace compared to the Biden years. Hegseth said Ukraine was a “European problem first” that required European funding leadership.

Democratic lawmakers in Washington criticized the review announcement, with the Senate Foreign Relations Committee’s ranking member saying it sent “exactly the wrong signal” at a moment when Russia was watching NATO cohesion carefully. Several Republicans with close military ties also expressed private reservations, according to sources familiar with internal party discussions.

The practical implications of the review will not be clear until it concludes in September. US European Command said in a statement that current operations and training exercises would continue without change while the review is underway. Allied military planners said they had not been given advance notice of the review’s scope or timeline.

Hegseth returns to Washington on Saturday and is scheduled to brief the Senate Armed Services Committee next week on the review’s parameters and what decisions it may produce.