NORFOLK, UNITED KINGDOM—US President Donald Trump, who has long sought to restore American strength and reassert his nation’s leadership role in global affairs, faces a moment that may ultimately define his legacy. He is a president who not only wants to win, but who also hates to lose—or to be seen as losing. That makes the stakes of the Pentagon’s ongoing review of US force posture in Europe exceptionally high, not only for Europe and the United States, but also for the president himself.
Launched in late July, the six-month European force posture review is needed to help transition the transatlantic alliance into what has been called NATO 3.0. In this new configuration, Europe is meant to assume responsibility for the conventional defense of the continent while the United States provides critical but more limited support. That transition will be enabled by European allies’ pledge to spend 5 percent of their gross domestic product annually on defense by 2035. However, that transition will take time and must be coordinated carefully to avoid weakening the Alliance at a time when it is vulnerable. A decision in the posture review based on ideology or vindictiveness must be avoided.
As the Pentagon conducts this review, the question confronting Washington is no longer simply how many of the roughly eighty thousand US forces deployed in Europe can be withdrawn without unacceptable military risk. Rather, it is whether the United States can afford the political, economic, and strategic costs of further eroding trust in its commitments. A collapse of trust among allies could reverberate far beyond the transatlantic relationship and reshape the United States’ global position for decades. The wrong decision would substantially diminish American power rather than restore and strengthen it.
The legacy question
Trump is acutely aware of his place in history. At age eighty, his behavior makes clear that he is thinking about his legacy. His ambition is to be a transformational leader: a president who restored American strength, ended wars, and reshaped US foreign policy for a new era.
Trump’s global legacy could turn on whether he chooses to stabilize the United States’ position in NATO—and take credit for transforming the Alliance—or weaken it from the inside. If he chooses the latter, the result could multiply the strategic costs of the Iran war and the trade wars the administration has launched against competitors and allies alike.
NATO matters because the United States’ global military posture depends upon access to European bases, logistics, intelligence, transit, communications, and early warning infrastructure. Facilities such as Fylingdales in the United Kingdom, Pituffik Space Base in Greenland, and North Warning System sites spanning Canada are not merely regional assets; they are integral to the United States’ global situational awareness.
The enormous and strategically vital bases at Ramstein, Mildenhall, Lakenheath, Fairford, and elsewhere in Europe are not simply platforms for European defense, but essential components of US global operations. For example, Ramstein alone hosts more than twenty thousand US military aircraft movements per year. Contrary to some administration rhetoric, these facilities remain heavily involved in operations related to the Iran war. The immense level of activity US bases in Germany, the United Kingdom, and elsewhere in Europe is a reminder that European infrastructure remains indispensable to US global force projection and the ability to rapidly surge forces.
The same applies to intelligence. The United States benefits enormously from surveillance, reconnaissance, and early warning capabilities distributed across Europe and the North Atlantic. These provide situational awareness that would be difficult, if not impossible, to replicate elsewhere quickly, inexpensively, or on an equivalent scale.
For decades, European forces have also contributed significantly to NATO and non-NATO military operations in the common interest, sharing the burden with, and sometimes relieving, the United States. These have included NATO operations in Bosnia, Kosovo, Afghanistan, Libya, Iraq, and off the Somali coast. European forces make up the bulk of NATO’s Enhanced Forward Presence posture in frontline states. The European Union has independently conducted about eighteen military operations since 2003, many of which benefit US interests as well. And Europe is now the primary provider of military assistance to Ukraine, including via purchasing US arms under the Prioritised Ukraine Requirements List (PURL).
This creates a paradox: A US administration that redistributes its global commitments too rapidly could undermine the very infrastructure, access, and troop contributions that enable the United States to exercise power globally.
The consequences of crossing red lines
As the administration moves forward with its posture review, it should avoid crossing five red lines. The United States should maintain:
- military leadership of the Alliance, carried out by an American Supreme Allied Commander Europe, or SACEUR;
- the US nuclear guarantee, including forward-deployed tactical nuclear weapons in the Dual-Capable Aircraft Program;
- US forward presence in some frontline allied states, along with the ability to rapidly reinforce these states;
- its enabling capabilities in Europe until US allies acquire sufficient replacement capabilities, ensuring that no strategic gaps emerge; and
- US access to European military infrastructure.
These are not concessions to Europe. They are vital to maintaining the instruments of American power.
Crossing any of these red lines could have consequences far beyond Europe. Consider these scenarios:
- A catastrophic but low-probability risk is miscalculation by Russia or China that drags the United States into war with a major power. Russia is already testing NATO resolve on a daily basis.
- A more probable outcome is a world in which coercion, hybrid warfare, nuclear threats, and terrorism all increase in frequency and severity.
- A slow restructuring of transatlantic trade in goods and services, currently valued at more than $1.6 trillion per year, could occur as partners turn away from the United States, putting more stress on the US economy.
- The United States could also lose access to European military infrastructure and arms trade, both of which are vital to its ability to project power globally.
Avoiding these scenarios requires ensuring that one quality more than any other endures in the Alliance, and that is trust.
Why trust matters
In some NATO countries, trust in Washington is already at an exceptionally low level. While some allies are prepared to ride out the current turbulence in the hope that the situation will change with the next administration, others believe the damage to be more profound. Signs already exist of nations seeking to reduce their dependence on US defense technology and industry wherever practicable.
The posture review should therefore not ask how many forces the United States can withdraw from Europe without unacceptable military risk. It should instead ask what decisions might cause US allies to conclude that Washington can no longer be relied upon.
If that judgment were to take hold, allies might hedge. Once they begin hedging, the process may be irreversible. The United States could find itself in a world in which its alliances are weaker, its access is constrained, its intelligence picture is degraded, its economic interests are threatened, and its adversaries are emboldened.
The right organizing principle for the ongoing European posture review is therefore clear:
Change where it makes strategic sense, but do not inadvertently destroy the political trust, military access, and infrastructure that make the United States a global power.
This is not about protecting Europe for Europe’s sake. It is about protecting American power, American prosperity, and American influence.