The key question for the US now is whether they are ready to provide security guarantees to Ukraine.

Trump may have raised unrealistic expectations among the American public about the leverage the United States can wield. But the key question for the United States itself is whether it is ready to provide security guarantees to Ukraine.

If this were to happen, one scenario for peace could be analogous to something like a truce between North and South Korea. Ukraine would have to agree to the continuation of the Russian occupation, although it would not have to formally condone it or give up its claims to its legally sovereign territory. Russia would have to agree that it would not encroach further on Ukrainian territory.

However, for Ukraine to even consider such an agreement, it must be backed by solid security guarantees. Essentially, this means focused US military power, since the Europeans cannot or will not provide security guarantees without the US.

In terms of troops and capabilities, the US does not necessarily need to dominate any Western military presence in Ukraine, but it should be prepared for significant escalation (presumably to the nuclear level) if the predominantly European "deterrence force" finds itself threatened by further Russian aggression.

For their part, the Europeans must be fully convinced that the United States will honor any such commitment. While the Europeans might be content with providing most of the troops and equipment for such a force, they would certainly demand some American presence on Ukrainian soil, sufficient to allow the United States to be quickly drawn into any military action with Russia.

This is, of course, the logic that operated in NATO’s European territory during the Cold War and returned with the forward positioning of American and European forces in Eastern Europe after Russia’s first invasion of Ukraine in 2014. Thus, while this would not necessarily be described as a NATO security guarantee for Ukraine, it would de facto come very close to one. Assuming such an agreement were acceptable to Ukraine, the next question is whether the US and Russia would agree to such an arrangement?

As for the US, comments this week from Defence Secretary Hegseth suggest that it is being cautious. Some influential US analysts and Trump supporters argue that the US lacks the military capacity to do so, given the need to balance China in the Indo-Pacific. Realistically, given the state of their armed forces and their own territorial defence responsibilities, the Europeans cannot provide such a guarantee themselves. And in the absence of such a guarantee, Ukraine is unlikely to sign a ceasefire that would leave it highly vulnerable to future Russian aggression.

Under such circumstances, they may decide to fight on. Although the Europeans are unable to offer Ukraine reliable security guarantees, they are deeply invested in Ukraine’s security and fear the consequences of an unbridled and unbridled Russia in Eastern Europe. They may therefore continue to support Ukraine with arms and aid, perhaps at a greater level. Thus, if the US tries to sponsor a deal without security guarantees and Ukraine refuses to agree, then Trump and the US risk being humiliated, especially if European allies continue to support Ukraine, as they have said they will.

Under these circumstances, could the US use leverage on Ukraine to persuade it to agree to a deal, for example by threatening to cut off military support and aid? Again, given the existential nature of the war for Ukraine, the encouragement of European support, and the resistance to such measures by influential figures in the US Congress, this seems unlikely to be effective. The US may then feel that it simply has no choice but to continue supporting Ukraine with arms supplies, and the war will continue.

On the other hand, if the United States is prepared to offer such a guarantee, will Russia agree to such terms? Much depends on Russia’s confidence in the sustainability of its military campaign and President Putin’s own political commitment to the war. There is evidence that the war is becoming increasingly unpopular in Russia, and of course it is causing serious economic discomfort through high inflation.

If Ukraine were confident in the West’s security guarantees, it might consider abandoning its desire to formally join NATO. Putin could then portray this and the annexation of part of Ukraine as a major victory. But would he be satisfied with NATO forces de facto protecting Ukraine? Wouldn’t that go against his whole reason for going to war?

If Putin hesitates about such an arrangement, can the US use additional leverage to help him make a decision? This could certainly threaten the continued and potentially increased military support for Ukraine and hit Russia with further sanctions. Given the West’s commitment to continued support for Ukraine and the continuation of painful sanctions, Putin might agree to such a truce. But he undoubtedly also has reasons to refuse, and so the war will continue.