How to defend Ukraine after a ceasefire
By Jennifer Kavanagh and Mark Leonard, European Council on Foreign Relations, 27 February 2026
Mark Leonard welcomes Jennifer Kavanagh to talk about Ukraine’s security architecture and the consequences of a US foreign policy that deprioritises Europe
As Russia’s full-scale invasion of Ukraine enters its fifth year, negotiations are finally entering a productive phase. Mark Leonard is joined by Jennifer Kavanagh, senior fellow and director of military analysis at Defense Priorities, and author of the new report, “An Armed Nonalignment Model for Ukraine’s Postwar Security”, to examine Ukraine’s security status and US foreign policy towards it. Mark and Jennifer explore her proposal that Ukraine should position itself as an “armed nonalignment” state, the future of the transatlantic alliance, and America’s National Defense Strategy.
Can Ukraine be nonaligned but also “armed to the teeth”? Could it become a porcupine that Russia cannot swallow? What should Europe and Ukraine do if future US foreign policy focuses more on the Indo-Pacific and the western hemisphere? Could Russia feasibly invade Ukraine again? And what happens if it does?
An armed nonalignment model for Ukraine’s postwar security
By Jennifer Kavanagh
Summary
Determining arrangements for Ukraine’s postwar security will be a critically important element of a negotiated end to the Russia-Ukraine war. A lasting peace will require an agreement that addresses both Kyiv’s fears about future Russian aggression and Moscow’s security concerns, including those focused specifically on Ukraine and those related to Europe’s security architecture more broadly.
The prewar status quo will not be acceptable to either combatant. In talks that have occurred since 2022, Moscow has consistently demanded that, in any war settlement, Kyiv accept territorial concessions and commit to permanent neutrality that would end Ukraine’s bid for membership in the North Atlantic Treaty Organization (NATO), limit its security ties with the alliance, and eliminate the prospect of NATO forces being based inside Ukraine.1 Moscow has also indicated that an acceptable deal would impose restrictions on Ukraine’s military capabilities to forestall the emergence of Ukrainian armed forces that are able to threaten Russian territory or Russian-occupied territory in Ukraine with long-range missiles and other capabilities. Ukraine has suggested that it will not accept a settlement that leaves it both without security guarantees or military partnerships and demilitarized so that it is unable to defend itself. To last, any agreement to end the war will need to leave Ukraine confident that it can, at the very least, deter aggression and defend itself if attacked.
In this report, I explore a possible model for Ukraine’s postwar security arrangements that might satisfy these competing security concerns and demands—a version of armed nonalignment that excludes membership in military alliances, such as NATO, but would provide Ukraine the military capabilities it needs to deter future attacks and defend itself if deterrence fails, without direct Western military intervention. Such a Ukrainian military force would serve as Kyiv’s primary assurance against future war, but it would lack capabilities to pose a real threat to Russia, thus addressing Moscow’s most serious concerns. For peace to take hold and endure, both sides will need to feel that a settlement sufficiently addresses their security concerns; Ukraine’s armed nonalignment offers a way to do so.
The purpose of this report is to examine how armed nonalignment could work in Ukraine, first by comparing it with potential alternative arrangements for Ukraine’s postwar security and then looking at the mechanics of such a model, including how Ukraine could establish its nonalignment and what would be required to defend the country sufficiently. With Western assistance focused on artillery ammunition, artillery rockets, and air defense, along with investments in Ukraine’s own defense production, Kyiv would need about five years after the settlement of the war to establish a strong and credible defensive posture that is sufficient to protect the territory under its control and hold off any future aggression.
Authors
Jennifer Kavanagh: Senior fellow, Defense Priorities
Mark Leonard: Director
