Where The Tracks Cross: How could a new war in Iran affect the prospects for peace talks and Moscow-Washington relations?

The outcome of the war in Iran, and even the duration of the military operation, will have a profound impact on the trajectory of US-backed Russia–Ukraine negotiations and the prospects for the continuation of military operations in Ukraine.

Detailed analysis shows that Iranian and Russian issues are closely intertwined within the foreign policy strategy of the Trump administration. Unlike the previous administration, Trump has prioritised the ‘Iranian problem’ from the outset, viewing the threats associated with it as existential.

In its approach to Iran and Russia, the new administration employed a strategy of ‘coercion to deal’, but in relations with Russia the emphasis has been on the appeal of a deal and the neutralisation of hostility, whereas in relations with Iran the focus has been on pressure and threat. A comparison of the two foreign policy tracks of the American administration — Iranian and Russian — reveals a connection between Trump's strategy shifts on both. reveals a clear link in the strategic shifts pursued by Trump across both fronts. The cessation of broad financial and military support to Ukraine by the US, combined with Trump’s alignment with Russian interests, allowed Moscow to withhold assistance to Iran in strengthening its air defence and air forces, despite persistent requests from Tehran.

Once it became clear that the twelve-day war had failed to achieve its strategic goal, that is the termination of Iran's nuclear and missile programmes, Moscow once again threatened to supply Tehran with Russian Su-35s, forcing Washington to ease the pressure on its side.

A potential success by Israel and the US in a second Iranian war, effectively neutralising the Iranian threat, would significantly weaken the Kremlin, which would lose one of its key assets in negotiations with Washington. Conversely, if the military operation descends into a protracted conflict or yields an ambiguous outcome, the Kremlin would be strengthened, since the threat of Russian military supplies to Iran would not only remain relevant but could even rise in value.

In Trump's world: the order turned upside down

The impact of a war in Iran on developments in the Russian–Ukrainian theatre of operations and negotiations can be considered along three main lines. First, the conflict could divert Donald Trump’s attention from the issue of a settlement in Ukraine. Second, it could have negative consequences for the supply of US weaponry to Kyiv, as arsenals are depleted in the Iranian war. Volodymyr Zelensky has already acknowledged that, in light of recent events, Ukraine may not receive the air defence system components it so desperately needs. Third, and finally, rising oil and gas prices and demand would alleviate the budget crisis in Russia and bolster its ability to continue military operations (→ Re:Russia: Temporary Beneficiary).

An additional bonus for the Kremlin is perhaps that, in justifying an attack on Iran, the US is using exactly the same rhetoric as Russia used to justify its aggression against Ukraine, pointing to a potential military threat allegedly emanating from a given territory (‘Our objective is to defend the American people by eliminating imminent threats from the Iranian regime’, Trump said in his eight-minute address to the nation). This reinforces Moscow’s position not only in legitimising its own aggression but also in pressing for conditions in a peace agreement with Kyiv that would include measures to ‘ensure the security’ of Russia, namely to limit Ukraine's military potential. Washington is putting forward roughly the same conditions to Tehran, focusing on the dismantling of nuclear and missile programmes.

However, this is merely the surface. The real influence of the ‘Iranian issue’ on the Russia–Ukraine settlement and on Moscow-Washington relations is likely far deeper and, in some respects, central.

From the very beginning of his presidency, Trump’s administration treated the containment of China as a core objective of US foreign policy, though its implementation was complicated by two concurrent, more specific issues: Iran’s nuclear programme and the Russia-Ukraine war. Hawks such as Secretary of State Marco Rubio viewed both countries as part of the ‘axis of anger’ and saw it as their task to confront them. At the same time, in contrast to Joe Biden, Trump adopted an isolationist stance towards the Russia-Ukraine conflict (‘This is not our war, it has nothing to do with the vital interests of the United States’). By contrast, the Iranian issue appeared as part of an ‘unfinished’ agenda from his first term.

Trump's withdrawal from the nuclear deal in 2018 is widely regarded as his worst foreign policy decision and one of the reasons why, by 2024, Iran was on the verge of developing a bomb (one example of this assessment → Responsible Statecraft: Killing the Iran nuclear deal was one of Trump's biggest failures). The Hamas attack on Israel effectively nullified the achievements of Arab-Israeli settlement, the hallmark of which had been the Abraham Accords, the main political success of Trump’s first term. Moreover, Trump was convinced that the Iranian leadership was behind two assassination attempts on his life. These circumstances determined a hierarchy of priorities in ‘Trump's world’ that was inverted compared to Biden's: the Iranian problem was significantly higher than the Russian one and, unlike the latter, seemed existential.

In its approach to both issues, the new administration used a ‘coercion to deal’ strategy,but with opposing emphases: in relations with Russia, the focus was on attractiveness, while in relations with Iran, it focused on pressure and threats. Just two weeks after his inauguration, Trump signed a memorandum declaring a doctrine of ‘maximum pressure’ on Iran. Then, in March, he proposed negotiations with Tehran and discussed them during his second telephone conversation with Vladimir Putin, alongside the Ukrainian settlement. Trump set a two-month deadline for the negotiations with Iran that began in April with Oman's mediation. Negotiations continued until the end of May and ended in failure: on 9 June, Tehran definitively rejected the US conditions. By 13 June, Israeli attacks on Iran triggered a twelve-day war, with the US joining in.

Notably, throughout the five months following his inauguration, Trump avoided exerting pressure on Russia despite European allies of Ukraine pushing for it. By late May to early June, amid an active Russian offensive, he even stated that peace was being obstructed by both sides, who needed to be allowed to ‘fight a little,’ which appeared like an overt encouragement to the Kremlin.

Moscow's perspective: an outcast as a useful asset

To resolve the Iranian issue, Trump apparently needed to secure Moscow's neutrality, primarily its refusal to assist Iran in restoring and strengthening air defence, intelligence systems, and in expanding its air force and ballistic missile arsenal. Russia supplied Tehran with S-300 systems in the mid-2010s, while the early 2020s were marked by periodically renewed negotiations over S-400 systems, components for air defence, and Su-35 fighter jets (for an overview of these discussions, see → FOI: Isolated together), which would undoubtedly have complicated matters for Israel and the US in the event of a military conflict with Iran.

Avoiding such supplies was all the harder for the Kremlin because Iran had provided significant support to Russia, supplying large batches of drones and even short-range ballistic missiles (Fath‑360) to the Russian army at a critical moment in the Russia-Ukraine war, expecting in return assistance with high-tech weaponry (→ Stimson: Iran and Russia enter a new level of military cooperation). In January 2025, Moscow and Tehran signed a broad strategic partnership agreement.

On the eve of and during the twelve-day war, Iran indeed attempted to secure Moscow’s support but was unsuccessful. At the height of the fighting, Iranian Foreign Minister Abbas Araghchi travelled to Moscow, where he received only verbal sympathy. Tehran’s disappointment was such that Iranian sources reported it to Reuters the following day, prompting Moscow to offer justifications. A senior Iranian official later remarked that \the war demonstrated the uselessness of the strategic alliance with Moscow’.

By late summer to early autumn, Trump’s rhetoric towards the Kremlin began to harden. Following a setback in Anchorage, he finally announced new sanctions, including additional tariffs against India as punishment for Russian oil purchases. At the same time, as Nikita Smagin, an expert on Russian-Iranian relations, noted, despite Moscow’s refusal to assist during the war, signs of cooperation between Moscow and Tehran began to increase again in autumn 2025. Official representatives of both countries announced a joint project to build a new high-capacity nuclear power plant in Iran and intensified planning for the southern transport corridor (‘North-South’). However, the real shock came in October 2025 when Newsweek published a leak regarding a $6 billion contract for 48 Russian Su-35 fighter jets for Iran, accompanied by reports of Russian Ruslan military transport flights to Iran.

October became the most tense month in relations between Moscow and Washington: Trump imposed sanctions against Russian oil giants Lukoil and Rosneft and unexpectedly raised the prospect of supplying Ukraine with Tomahawk missiles. These threats, however, subsided after Trump's telephone conversation with Putin on 16 October (→ Re:Russia: Groundhog Year or Double Game?).

Meanwhile, with regards to Iran, it became clear by this point that the twelve-day war did not destroy Iran's nuclear potential, and that Washington was making a new attempt to negotiate a nuclear deal with Tehran. However, Iran has consistently denied IAEA inspectors access to Natanz, Fordow and Isfahan – three key nuclear facilities damaged by the US and Israel during the twelve-day war, where stocks of enriched uranium may remain. The publicised dispute between Tehran and the IAEA in November signalled the prospect of a new conflict in Iran, and almost simultaneously, a new Russia–Ukraine peace plan emerged, based on proposals by Kremlin special envoy Kirill Dmitriev, the discussion of which continues to this day.

Although initially appearing parallel, the Iranian and Russian tracks in the Trump administration’s policy reveal clear intersections on closer examination. The threat of sensitive military supplies to Tehran from Moscow has existed since early 2025 and appears to have been skilfully leveraged by the Kremlin. The Iranian regime is not only Russia's situational ally in its confrontations with the West (as, for example, during the early stages of the Ukraine war), but also its long-standing strategic asset in negotiations with the US, Europe and Israel. In the 2000s, Moscow initially supported Iran's right to ‘peaceful atom’ and then voted for all UN Security Council resolutions against Iran in 2006–2008 (→ OSW: Russia plays the Iran card with the USA). In 2007, Russia signed a contract to supply S-300 systems to Iran, but delayed execution and ultimately cancelled it in 2010. Deliveries were eventually completed in 2015, after Russia’s relations with the West sharply deteriorated following the annexation of Crimea.

Analysing the two tracks of US policy — Iranian and Russian — it can be concluded that Moscow has leveraged this asset twice over the last year: first, during the initial ‘negotiation–war’ round between Tehran and Washington (January–June 2025), and second, in the later round (September 2025–March 2026), securing more favourable positions in both theatres of war and negotiation with Ukraine.

This view of the events of the past year and the interaction of Trump's two policy tracks raises two questions. First, has Moscow already reaped the dividends of its neutrality during the second war in Iran, or is it still waiting for them? Second, how and when will the second war end? Clearly, a significant success by Israel and the US, resulting in the elimination of the Iranian threat, would weaken Moscow, which would lose a key bargaining asset with Washington. Conversely, if the military operation becomes a protracted conflict or ends ambiguously, as in June, Moscow would benefit, as the threat posed by potential Russian military supplies to Tehran would remain relevant or even increase in value (for more on current analyst and expert assessments on the likely outcomes of the war, see our review The Fog of Victory.)