Trump's Iran war is killing Ukraine peace prospects

President Donald Trump came into office promising to end wars, but last week, he instead started a new one, when he ordered what the White House is calling a “proactive defensive” operation in response to Iran’s “imminent threat.”

The onset of yet another U.S.-initiated conflict in the Middle East deals a double blow to Trump’s ambitions as a peacemaker. It has obviously derailed, perhaps permanently, the on-and-off talks between Tehran and Washington over the future of Iran’s nuclear program. But it is also likely to interfere with another Trump priority: ending the four-year-long war between Russia and Ukraine.

The conflict in Iran probably won’t alter the long-term trajectory of Russia’s special military operation. It will, however, prolong the fighting and make it harder to reach a ceasefire. Not only does the Iran war fallout weaken U.S. leverage over both combatants, but its economic and military consequences will give both Kyiv and Moscow incentives to slow-walk diplomatic efforts. A breakthrough is still possible, but these setbacks mean peace in Ukraine is likely a long way off.

It would be a stretch to say that U.S.-mediated talks between Russia and Ukraine over the early months of 2026 were successful, but by all accounts, progress has recently been meaningful if slow. For example, U.S. officials reported that the two sides had reached some agreements on post-conflict ceasefire monitoring. Most of the big issues, such as security guarantees for Russia and Ukraine, Ukraine’s military capabilities and alignment, NATO expansion, and territory, have yet to be resolved. But all parties seemed optimistic that with time and consistent meetings, a deal could be reached.

Now, about a week into the U.S. war in Iran, the picture looks much murkier. Peace talks seem to have stalled, with little information or interest from the Trump administration about the timing or agenda for the next round.

Some obstacles to continued talks are logistical in nature. For example, the war’s rapid escalation makes meetings in places like Abu Dhabi impossible. Bandwidth within the U.S. government is another likely constraint. Special Envoy Steve Witkoff may have time on his hands now that negotiations with Iran are indefinitely suspended, but other key players in the State and Defense Departments will be busy managing the domestic and global ripple effects of President Trump’s Middle East war. They may simply not be available for repeat trips to neutral locations in Europe or elsewhere.

Other impediments to the diplomatic process are more pernicious.

For starters, the conflict’s effect on global oil prices and supplies will give Russia’s flagging economy new life and could decrease Moscow’s interest in negotiations. Economic pain was never likely to be the reason Russian President Vladimir Putin decided to end the war, but with the conflict in the Middle East scrambling oil exports and triggering sharp increases in prices and demand for Russian oil, the Trump administration has lost any economic leverage that it might have had.

At least since last November, the Trump administration’s hope was that slowly squeezing Russia’s oil revenues would eventually force Moscow to accept greater compromise at the negotiating table. To that end, Trump imposed new sanctions on Russia’s oil industry, pressured India to cut its purchases of Russian oil, and stepped up the campaign against Russia’s shadow fleet.

Now, with tanker traffic through the Strait of Hormuz effectively paused, the Trump administration has been forced to recalibrate its approach. The U.S. Department of Treasury has already eased pressure on Russian oil exports, announcing on March 5 that it would allow (even encourage) India to resume purchases of Russian oil for 30 days without penalty. At the same time, U.S. interest in chasing Russia’s shadow fleet has diminished. Not only are many U.S. naval and air assets tied up in the Middle East, but with Trump eyeing gas prices as a key piece of his “affordability” agenda domestically, Washington needs Russian oil in the market to help keep costs down.

The economic windfall Russia receives from the Iran war’s disruption of trade may endure only over the short-term. But even limited relief will give Moscow the income necessary to put off painful structural changes to the Russian economy for some time. At the very least, higher oil revenues will give Putin more options when it comes to financing his war effort.

U.S. military operations in the Middle East could also affect the military balance inside Ukraine in ways that make negotiations less appealing to Moscow.

Rapid expenditure of U.S. air defense and munitions against Iran will drain stockpiles and reduce what is available to support Ukraine’s self-defense. Ukraine can produce much of its own military equipment now and is entirely self-sufficient in the production of the drones needed to freeze Russian offensives. It still relies on the United States, however, for air defense interceptors—the same weapons that are needed today in large quantities by U.S. forces and Gulf partners.

If U.S. air defense shipments to Ukraine dwindle, it will not necessarily change things on the battlefield right away, but it will leave Ukraine’s civilian and industrial infrastructure vulnerable, damaging its defense materiel production and its civilian population over time. Whether the military, industrial, or civilian effects of the loss of U.S. support will be large enough to push Ukraine toward bigger concessions is uncertain, but Putin and his advisers may be willing to wait and see, hoping that this will be the case.

At the same time, Ukraine may see new reasons to drag out negotiations as well. Specifically, the success of the most hawkish elements of Trump’s coalition in persuading him to attack Iran may give Ukraine reasons to hope that a successful Middle East war will further empower the U.S. factions most in favor of taking a hardline on Russia as well. This might open the door to harsher sanctions on Russia and more military aid to Ukraine in the future. Such an outcome seems unlikely given Trump’s consistent opposition to these moves, but with little to lose, Ukraine’s leaders may take the chance.

The most serious hurdle facing U.S. efforts to end the war in Ukraine, however, affects both combatants equally: Washington’s loss of credibility as a mediator. Twice now, in June 2025 and last week, the United States has attacked Iran during negotiations. Some participants of the most recent round of diplomacy have suggested that the talks were a sham, meant as a distraction while the United States and Israel prepared for war. The Gaza ceasefire that the Trump administration negotiated has similarly proved to be partial at best. Hostages were released, but Israeli airstrikes did not stop.

At this point, it is not clear that either Kyiv or Moscow trusts that Washington can deliver on a deal or make good on its security promises to each side. For its part, Russia may fear that any guarantees from the United States on Ukraine’s neutrality or NATO expansion will be as empty as those verbal promises offered to Iran. Ukraine, meanwhile, will rightly worry that it will make painful concessions but still be left with no binding security commitments from the United States and no way to prevent the return of war on Russia’s terms.

This lack of trust in the United States as mediator is fatal to any U.S.-led diplomatic effort and will be hard to overcome even once the war in Iran ends. With no confidence that talks will address their underlying security concerns or lead to a durable armistice, both Russia and Ukraine are likely to choose continued war, gambling on battlefield gains as the better path to security.

If Trump is serious about ending the war in Ukraine, his administration should start thinking now about what will be required to rebuild Washington’s credibility as a negotiator and diplomatic broker. Options might include adding new faces to the core of the U.S. negotiating team or beginning serious discussions domestically and internationally about how post-war security assurances can be codified and made legally binding alongside any ceasefire.