The Impact of the Expiration of the New START Treaty on the Security of Central and Eastern Europe

On 5 February 2026, the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms (New START), concluded in 2010 by the United States and Russia, expired. Although the treaty did not cover the systems used by Russia for nuclear coercion against the states of Central and Eastern Europe (CEE), its termination has global implications and therefore indirectly affects the security of the region.

The Road to New START. On 5 February 2026, the treaty between the United States of America (USA) and the Russian Federation on the reduction of strategic offensive arms—commonly referred to as New START—expired. It constituted another agreement in the series of arms control treaties concluded since 1972 between the USA and the USSR/Russia, beginning with the SALT agreement signed by Richard Nixon and Leonid Brezhnev. SALT limited the number of defensive systems (anti-ballistic missile systems) and solidified the principle of mutual assured destruction (MAD) as the foundation of nuclear stability.

An attempt to move beyond the logic of MAD was subsequently undertaken by President Ronald Reagan. Although the START I treaty drafted in1982, it was ultimately signed only in 1991 by George H. W. Bush and Mikhail Gorbachev. The treaty led to the largest reduction of nuclear weapons in history, decreasing the available arsenals (primarily measured in numbers of nuclear warheads) by approximately 80%—to around 6,000 warheads and 1,500 strategic delivery systems.

New START was signed in 2010 by Presidents Barack Obama and Dmitry Medvedev and entered into force on 5 February 2011. In 2021, it was extended for a further five years by Presidents Joe Biden and Vladimir Putin. This extension was, however, conditional and resulted more from negotiating impasse than from a genuine intention to deepen détente. Since at least 2019, the United States has pressed for the inclusion of the People’s Republic of China as a third party to any future agreement, a proposal opposed by both Russia and China. New START provided for a reduction in the total number of deployed (i.e. operationally ready) warheads to approximately 1,550, deployed missiles to 700, and total launchers to 800[1].

Demythologising New START and the Consequences of Its Expiration. An assessment of the consequences of the expiration of New START for global security and for the regional security of CEE requires emphasis on several key points.

First, the treaty neither eliminated strategic nuclear weapons nor reduced them to a level that would eliminate the logic of MAD. The number of warheads and delivery systems remained sufficiently high to produce, in a hypothetical scenario, a “global catastrophe”.

Secondly, New START concerned only strategic and intercontinental systems. Tactical nuclear weapons and systems such as Kalibr, Iskander, Oreshnik, or the Poseidon torpedo—frequently invoked in the context of nuclear coercion against certain CEE states—were not covered by the treaty[2].

Thirdly, the treaty had de facto ceased to function on 21 February 2023, when Russia suspended its participation. Its formal expiration therefore merely sealed an existing reality.

The International Context of the Treaty’s Conclusion and Expiration. From the perspective of the United States, the conclusion of New START formed part of the broader policy of the Obama administration, centred on the Pacific Pivot and the associated “reset” in relations with Russia. In November 2011, then Secretary of State Hillary Clinton stated in Foreign Policy that the Indo-Pacific region would be the principal determinant of global politics and, consequently, of US foreign and security policy[3]. The reset with Russia—of which New START was emblematic—thus constituted an attempt to stabilise bilateral relations, and perhaps even to establish closer cooperation with Russia, in light of the need to concentrate capabilities on competition with China.

During the first Donald Trump’s term, difficulties in the field of bilateral nuclear agreements became apparent. Trump openly refused to extend New START and in 2019 withdrew from the Intermediate-Range Nuclear Forces Treaty (INF). Despite these tensions, under President Biden both parties agreed to a conditional five-year extension of New START.

Russia’s full-scale invasion of Ukraine in February 2022 created a fundamentally new strategic environment for New START. The failure of the so-called “special military operation” prompted recourse to nuclear coercion. This, combined with Moscow’s belief that it would soon overcome difficulties on the Ukrainian front and eventually resume competition with the United States on equal footing in the nuclear domain, led Russia first to refuse inspections and information-sharing regarding its nuclear arsenal and subsequently, in 2023, to suspend its participation in the treaty.

Prior to the expiration of New START, Russia sought its further extension. However, the international conditions at the beginning of 2026 differed markedly from those of 2023, when Russia de facto withdrew from the agreement. Russia’s interest in extending the treaty stemmed from the fact that the United States enjoys certain structural advantages: significant warhead reserves; the capacity to produce more advanced delivery systems (the Golden Dome); the development of missile defence capabilities; a declared readiness to deploy systems beyond US territory; and the demonstrative testing of intercontinental ballistic missiles (Minuteman III).Under wartime conditions, Russia cannot easily replicate such measures.

The political dimension is equally important. Treaties such as New START constitute a significant element of strategic communication, signalling levels of tension and the overall condition of bilateral relations. A renewed US–Russian agreement would therefore have carried important political symbolism, potentially usable by Russia in the context of the ongoing negotiations concerning the war in Ukraine. The United States, however, seeks to include China in future arms control frameworks, given the steady expansion of its nuclear potential[4].

Consequences for the States of Central and Eastern Europe. The implementation of New START had no direct impact on the security of CEE states, against which Russia employed nuclear intimidation using tactical systems not covered by the treaty. Nevertheless, the expiration of an agreement that had already ceased to operate in practice may be instrumentalised by Russia in informational and cognitive operations targeting the societies and decision-makers of CEE countries. The treaty’s expiration has revived discussion of nuclear weapons in the information sphere, providing an opportunity to reiterate Russia’s status as a “nuclear power”. This may elevate overall levels of tension and anxiety as well as increase fears of confrontation in CEE.

The erosion of the international security architecture and the gradual withdrawal of the United States from the role of primary security provider may render the nuclear deficit on NATO’s eastern flank increasingly visible and politically salient—particularly given that the principal adversary of CEE states possesses a nuclear arsenal and demonstrates willingness to engage in nuclear coercion.

This dynamic has revived debates within CEE states concerning the acquisition of a nuclear umbrella, whether in the form of strengthened allied capabilities or autonomous efforts. Similar discussions are underway in other states that have traditionally relied upon close security partnerships with the United States, including South Korea and Australia. Sweden has also initiated steps in this direction—effectively revisiting Cold War-era concepts—as announced in January 2026 by Prime Minister Ulf Kristersson.

The articulation of an intention to acquire nuclear weapons by CEE and Northern European states may also serve as a bargaining instrument vis-à-vis allies that possess nuclear capabilities yet seek to prevent proliferation, for example in order to secure greater engagement in conventional deterrence.

[1] The methodology for calculating arsenals across the respective categories is more complex than the simplified depiction presented in this analysis.

[2] For further discussion of NATO’s response to nuclear coercion, see “IEŚ Commentaries”, no. 1117.

[3] H. Clinton, America’s Pacific Century, 11.10.2011, https://foreignpolicy.com/2011/10/11/americas-pacific-century/ [11.02.2026].

[4] Hans M. Kristensen and Matt Korda, World Nuclear Forces, in: SIPRI Yearbook 2025: Armaments, Disarmament and International Security, Stockholm International Peace Research Institute, available at: https://www.sipri.org/sites/default/files/SIPRIYB25c06%266A.pdf.

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