tions to Ukraine(Quinville et al. 2024; Rough 2024, p. 25). Others think that these efforts fall far too short of what is really needed in terms of much more equitable bur­den-sharing across the Atlantic. For instance, Robert Greenway and Nile Gardiner think that Europe should spend as much on defense as the US in terms of GDP (Greenway and Gardiner 2024). This would amount to about 3.5 percent or more – a figure that is now already becoming the new yardstick in NATO debates. Those impatient voices are generally also in favor of put­ting much more political pressure on Europe. One proposed way to do so is to create a burden-shifting roadmap with specific time frames and milestones – combined with the implicit or explicit threat of punishment if European states fall short of their commitments(Peters 2024, p. 19). Penal ­ties could even include withdrawal of US troops from Eu­rope or make US security guarantees conditional on how European states fulfill their commitments(Logan 2023, p. 15). Probably the most outspoken proponent of a“forceful” approach is Sumatra Maitra who has been seen as close to Trump’s thinking on NATO. He distinguishes between bur­den sharing and burden shifting.“Burden sharing is a col­laborative process …. Burden shifting is a unilateral exer­cise of power driven by American interests. It provides a rapid and firm timeline, forcing Europe to plan resources and alternatives”(Maitra 2023). Another aspect of the burden-sharing debate addresses how to define the burden that is to be shared. Many of those who want Europe to spend more on defense view this aspect of the debate as a distraction. For them, it is the simplicity of taking the“military expenditure to GDP ratio” as the prin­cipal goal-post that makes it so attractive. Others hold that this simple metric does not adequately reflect NATO’s needs and contributions. A recent RAND study proposes defining burden sharing in broader terms to include defense/non-de­fense inputs and outputs, such as the quantity and quality of armed forces, contributions to peacekeeping operations, and even the share of lost exports due to sanctions(Mallory et al. 2024, p. xi). Similarly Kathleen McInnis and Daniel Fata propose widening the burden-sharing metric beyond NATO’s current methodology to include activities that are also critical for NATO security, such as peacetime prepared­ness and resilience(McInnis and Fata 2023, p. 1). It remains to be seen how the most recent decisions by Germany and the European Union to significantly increase defense spending will affect the US debate. Will conser­vatives and conservative populists see these decisions as a game changer, demonstrating how Trump’s threats to Ukraine and NATO have forced Europeans to step up? Will Trump and his followers now see NATO as a“better deal” than before? While the burden-sharing debate is often cast in the nar­rower terms of financial contributions, it also involves a more structural and institutional dimension. The core ques­tion in this regard is whether European defense will be real­ized through the Europeanization of NATO, through a radi­cally recast NATO or through something completely outside of it. Obviously, Atlanticist-oriented voices call for revitali­zation of NATO by strengthening its European pillar. The assumption here is that the US will remain the indispensa­ble leader in the Alliance. In this spirit, the Alphen Group propose specific timelines and numbers to enhance Europe­an allies’ share of NATO’s combined operational capacity for collective defense(67 percent by 2035). They also pro ­pose creating a“European-led, division-strength, air, sea, and land force that by 2030 takes the Allied Response Force to a new level of capability to underpin deterrence by denial in all circumstances”(The Alphen Group 2025, p. 8). Proposals for NATO’s Europeanization include a reform of its Command and Control(C2) structure to ensure that the European allies take on more responsibility from the Unit­ed States. However, as Luis Simon and others stress in a paper published by the Marathon Initiative,“any effort to expand Europe’s influence in NATO’s C2 architecture should respect the overarching principle of U.S. leadership, embodied in the position of Supreme Allied Commander Europe(SACEUR)”(Simon et al. 2023, pp. 12–3). In their view, a European SACEUR would weaken the credibility of US assurances while Europeans might be unable to agree on a replacement from their ranks. According to media re­ports, the Trump administration is indeed thinking about the option of replacing SACEUR with a European commander (Kube and Lubold 2025). Another important aspect of NATO reform concerns the Alli­ance’s decision-making process, which is based on the con­sensus principle, albeit informally for most topics. Some think-tank analysts consider allies such as Hungary and Slovakia as problems for the Alliance’s ability to respond to the Russian challenge. Their idea is that the Alliance should introduce a majority voting procedure, especially in the con ­text of critical Article 5 situations. Eric Edelmann, David Manning, and Franklin Miller stress that such a reform “would make it impossible for one member state to serve Russia’s interests by insisting on the consensus principle, thereby paralyzing the Alliance’s ability to defend an ally from Russian aggression”(Edelman et al. 2024). As Ira Straus points out, NATO has made decisions without con­sensus in the past, for instance by using a“silent proce­dure” or the“consensus minus one” rule(Straus 2023). In his view, it would be important to revive this kind of flexi­bility in NATO’s decision-making. However, these reform proposals do not address a situation in which the major political and military power in the Alliance, the United States itself, becomes the major troublemaker. Trump’s return to the White House raises the prospect that NATO will face a much more radical overhaul or even an existential crisis. Anticipating a possible Trump return even before the 2024 elections, Max Bergman saw the status of NATO – whereby“NATO is organized around European forc­es essentially docking into a U.S.-led campaign plan” – as no longer sustainable. Instead, he recommends taking the Burden Sharing, Europeanization, and NATO’s Internal Adaptation 9