Recent talks in Berlin have brought renewed focus on Western security guarantees to Ukraine. In mid-December 2025, U.S. envoys at the behest of President Donald Trump offered Kyiv unprecedented NATO-style assurances. U.S. officials reported that the American side was prepared to provide “security guarantees that are equivalent to Article 5” of the NATO treaty.[1] Ukraine’s president thanked the U.S. for this initiative, calling it a “first step.” European leaders cautiously welcomed the offer, but noted it must be backed by concrete defense measures. German Chancellor Friedrich Merz said Ukraine “will be able to defend itself in the long term … with the support of the states allied with Ukraine”,[2] stressing that allied military backing is essential.

Trump’s peace plan underscores his transactional view of alliances. The draft 28-point framework explicitly commits the U.S. and European allies to treat any Russian attack on Ukraine as an attack on the entire transatlantic community, obliging them to respond “including through military force”.[3] This promise of collective defense is the strongest form of deterrence short of NATO membership. However, the utterances of Trump himself have put a question mark. He has described the war as one which would have never occurred under his presidency and he pointed the blame on failures on the leaders of Ukraine. He informed the reporters that Ukraine had lost a lot of land, and this is also good land, and Ukraine has to have elections regardless of the war.[4] Such remarks highlight his transactional position: the security guarantees are directly linked to Ukrainian concessions.

From a Foreign Policy Analysis standpoint, leadership decisions and domestic institutions loom large. Any formal U.S. security treaty would require Senate consent; as one official noted, it “would have to go before the Senate,” and Trump said he would seek approval.[5] For example, any U.S.–Ukraine pact would need Senate ratification by a two-thirds vote. Congress has already acted: Lawrence Freedman notes that the U.S. Senate passed a bipartisan bill barring any president from withdrawing from NATO without its consent.[6] These checks constrain how far an administration can extend U.S. commitments. The situation is mirrored in Kyiv: analysts note that in 1994 Ukraine “gave up the world’s third-largest nuclear arsenal in exchange for promises later violated by Russia”[7], making Ukraine especially wary of guarantees lacking strong enforcement. Zelenskiy has even indicated he could drop Ukraine’s NATO membership bid in return for U.S. and allied assurances, highlighting how Ukraine is willing to sacrifice its membership goal for credible guarantees.

Alliance coordination is equally critical. European leaders and NATO partners insist that Ukraine’s security must depend on collective action. In Berlin a bloc of EU and NATO heads agreed that any Ukrainian territorial concessions must be matched by “robust guarantees,” including a European-led peacekeeping force backed by Washington.[8] They envision Ukraine maintaining a roughly 800,000-strong army to deter aggression, supported by a rotating multinational force of willing countries. In fact, a recent joint European proposal specified keeping Ukraine’s army around 800,000 and deploying a U.S.-backed European security force.[9] Zelenskiy went further, emphasizing that Article-5–style pledges from the U.S. and Europe – along with commitments from allies like Canada and Japan – were necessary “to prevent another Russian invasion”.[10] The allied communiqué even calls for a “legally binding commitment” to use force if Ukraine is attacked, implying only enforceable guarantees will reassure Kyiv.

The stakes of these guarantees are emphasized in the extended deterrence theory. The credibility of NATO is long-established based on the U.S. nuclear ability and conventional ability; charter is based on nuclear first-use deterrence policy.  While, Ukraine is not a NATO member and any new guarantees will not be based on an automatic treaty commitment, but instead on a pure political desire and alliance. Practically, Ukraine is still reliant on the goodwill of its allies instead of some legal assurance. The case of Ukraine in 1994, when it gave up its nuclear weapons in exchange of security guarantees which were broken thereafter is a classic example cited by analysts to be used as a lesson. It is this past that has rendered Kyiv extremely distrustful: any novel pledge should be tangible, multilateral, and lasting to rebuild deterrence.

The evolving proposals reflect a balance between ambition and constraint. They mirror Trump’s high-stakes negotiation style – trading U.S. guarantees for Ukrainian concessions – and European insistence on collective backing. At the same time, they are bounded by institutional realities: U.S. constitutional checks, NATO consensus rules, and Ukraine’s demand for legally credible commitments. As Polish Prime Minister Donald Tusk warned, only guarantees given “in such a way that the Russians would have no doubt that the American response would be military if the Russians attacked Ukraine again” can truly deter aggression. He emphasized that without such visible allied backing, even Article-5–style promises would not be credible. The proposals thus navigate between Kyiv’s demand for ironclad defense and the mechanics of alliance politics – a classic FPA puzzle of leadership, institutions, and extended deterrence.

Muhammad Ibrahim is an independent researcher and analyst, and a student of International Relations at the National Defence University, Islamabad.

[1] Andreas Rinke et al., “US Dangles Security Guarantees for Ukraine but No Deal on ‘painful’ Territorial Concessions,” Reuters, December 16, 2025, https://www.reuters.com/world/europe/ukraine-peace-talks-stretch-into-second-day-start-pivotal-week-europe-2025-12-15/.

[2] Michael Birnbaum et al., “U.S. Offers Ukraine Security Guarantee in Bid to Strike Peace Deal,” The Washington Post, December 15, 2025, https://www.washingtonpost.com/politics/2025/12/15/us-ukraine-security-guarantees/.

[3] Barak Ravid, “Trump Peace Plan for Ukraine Includes NATO-Style Security Guarantee,” Axios, November 21, 2025, https://www.axios.com/2025/11/21/ukraine-security-guarantee-nato-article-5-trump.

[4] Russia Matters, “Russia Analytical Report, Dec. 8–15, 2025.”

[5] Russia Matters, “Russia Analytical Report, Dec. 8–15, 2025.”

[6] Lawrence Freedman, “Trump, NATO, and Nuclear Deterrence,” Substack newsletter, Comment Is Freed, February 18, 2024, https://samf.substack.com/p/trump-nato-and-nuclear-deterrence.

[7] Luke Coffey, “What Western Security Guarantees for Ukraine Might Look Like,” Defense One, August 25, 2025, https://www.defenseone.com/ideas/2025/08/what-western-security-guarantees-ukraine-might-look/407670/.

[8] “European Leaders Agree Ukraine Security Guarantees Should Include European-Led Peacekeeping Force,” Europe, Reuters, December 16, 2025, https://www.reuters.com/world/europe/european-leaders-agree-ukraine-security-guarantees-should-include-european-led-2025-12-15/.

[9] Birnbaum et al., “U.S. Offers Ukraine Security Guarantee in Bid to Strike Peace Deal.”

[10] Friederike Heine et al., “Ukraine Drops NATO Goal as Trump Envoy Sees Progress in Peace Talks,” Europe, Reuters, December 14, 2025, https://www.reuters.com/world/europe/zelenskiy-demands-dignified-peace-us-ukraine-officials-meet-berlin-2025-12-14/.