Why It Matters

More than four years into Russia's full-scale invasion of Ukraine, the Congressional Research Service is putting Congress on notice: the diplomatic path to ending Europe's largest war since World War II is waning. Stalled talks, competing demands from both sides, and the ripple effects of U.S. military operations in the Middle East are the main reasons.

The report, updated May 22, 2026, lays out the state of Russia-Ukraine war diplomacy with stark clarity. Estimates range from 1.3 million to 1.8 million killed or wounded. Russia controls roughly 20 percent of Ukrainian territory. And neither side appears positioned to win outright on the battlefield. And fighting on both sides has heated up in recent days.

The Big Picture

The second Trump Administration had said ending the Russia-Ukraine war would be a signature foreign policy priority. Building on talks that began in 2025, Russian, Ukrainian, and U.S. officials met for the first time in a trilateral format in Abu Dhabi in January 2026. Follow-on U.S.-mediated sessions took place in Abu Dhabi and Geneva in February 2026.

Then the talks stopped.

Formal negotiations between Russia and Ukraine have not resumed since U.S.-Israeli military operations against Iran began in late February 2026, according to the report. The two tracks, one aimed at Middle East stability and one aimed at European security, appear to have collided, with the Iran operations consuming diplomatic bandwidth and creating new complications for the Ukraine negotiating track.

The fundamental divide between the parties remains unresolved. Ukrainian officials have long favored securing a sustained ceasefire before addressing the broader terms of a settlement. Russia has pushed for a comprehensive agreement that would, in its preferred form, include Ukrainian neutrality, constraints on Ukraine's military capacity, and Russian occupation of additional Ukrainian territory that Moscow claims to have annexed but does not fully control.

Those are not minor differences. They reflect incompatible visions of what a post-war order looks like, and they have resisted resolution across multiple rounds of diplomacy.

The NATO Question

Ukraine's ask goes beyond a ceasefire. Ukrainian officials have sought firm guarantees against future Russian aggression, including deployment of Western peacekeeping forces and deeper integration with NATO and the European Union.

The Trump Administration has indicated that NATO membership for Ukraine is unrealistic. At the same time, Administration officials have expressed support for European-led security guarantees, with possible U.S. involvement. Ukraine has asked Washington to formally pledge support for those guarantees as part of any postwar agreement. U.S. authorities have reportedly responded that Ukraine and Russia must first reach a deal before such a pledge would be considered.

The result is a circular problem: Ukraine wants guarantees before agreeing to terms, and the U.S. wants an agreement before offering guarantees. The precise nature and form of any potential guarantees, the report notes, remains uncertain.

War Diplomacy

On military assistance, the Trump Administration has not announced new security aid to Ukraine, though it has continued delivering on previously committed packages. The more significant development is structural: the Administration has moved to shift the financial weight of supporting Ukraine onto European allies.

The vehicle for this is the Prioritized Ukraine Requirements List, or PURL, an initiative launched with NATO allies in which partner nations fund the transfer of U.S.-sourced defense articles to Ukraine. As of March 2026, NATO allies and partners had contributed more than $4.1 billion through PURL.

In April 2026, a U.S. defense official stated that the United States is "prepared to continue helping through initiatives like PURL, but this support must not rely on significant U.S. contributions." That framing signals a deliberate posture: Washington will facilitate, but Europe will fund.

Some NATO and European officials have reportedly expressed concern that U.S. military operations against Iran could lead to procurement shortages and delays that affect assistance to Ukraine, adding another layer of uncertainty to an already strained supply picture.

Ukraine, for its part, has pursued new defense cooperation agreements of its own, signing arrangements with Saudi Arabia, Qatar, the United Arab Emirates, and Germany, with a particular focus on drone and anti-drone warfare capabilities.

For FY2026, Congress authorized $400 million in security assistance to Ukraine, with an equivalent increase in appropriations for European capacity building security cooperation programs.

Sanctions: Maintained, Expanded, and Then Quietly Eased

The Trump Administration has kept most previously established U.S. sanctions on Russia in place. In October 2025, the Treasury Department listed new entities, most notably Russia's two largest oil companies, Rosneft and Lukoil, along with several subsidiaries.

But the sanctions picture is more complicated than it appears. Following the start of U.S.-Israeli military operations against Iran, Treasury issued two General Licenses to help stabilize global oil markets. The licenses authorized, for a limited period, transactions involving the sale, delivery, or offloading of Russian crude oil or petroleum products. The second of these licenses has been extended twice. Under GL134C, such transactions are currently authorized for products loaded on or before April 17, 2026, through June 17, 2026.

The carve-out applies globally, with exclusions for transactions involving Iran, North Korea, Cuba, and Russia-occupied areas of Ukraine.

The practical effect is a policy tension: the Administration has expanded sanctions on Russian energy companies while simultaneously issuing licenses that facilitate revenue from Russian oil sales. Congress may scrutinize that gap.

Political Stakes

For the Administration

The Trump Administration has staked significant political capital on its ability to broker a deal that ends the war. Stalled talks, a stalled ceasefire, and a still-active conflict four-plus years in create pressure on that narrative. The Administration's posture, pushing Europe to carry more of the financial load while positioning the U.S. as a facilitator rather than a primary backer, may reduce domestic political exposure but raises questions about whether the U.S. retains enough leverage to close a deal.

For Congress

The CRS report frames Congress as holding meaningful tools it has not yet fully deployed. Members can authorize, appropriate, restrict, or conduct oversight over further assistance to Ukraine. On sanctions, several pieces of legislation are in play, including S. 1241 and H.R. 2548, which would impose or strengthen sanctions against Russia if it refuses to negotiate or violates any agreement, as well as S. 2904, S. 3513, and H.R. 6856. On the assistance side, H.R. 2913 and S. 2592 are referenced in the context of further Ukraine support.

The report notes that Congress may also evaluate the impact of negotiations on U.S. relations with NATO allies, a consideration that cuts across both parties.

For Ukraine and European Allies

Ukraine faces a difficult position: it needs security guarantees to accept any deal, but the U.S. has conditioned those guarantees on a prior agreement. European allies are being asked to shoulder more of the military and financial burden at a moment when procurement pipelines are already under strain. And the humanitarian dimensions of the conflict, including prisoner exchanges, the return of civilian detainees, and the fate of forcibly transferred populations including children, remain unresolved.

The Bottom Line

The CRS report maps the distance between where the parties are and where they would need to be. That distance is considerable.

The Trump Administration controls the diplomatic steering wheel on Russia Ukraine war diplomacy, but Congress retains significant leverage through appropriations, sanctions authority, and oversight. The report is, in effect, a checklist of decisions that remain unmade.

With formal talks stalled, security guarantees unresolved, and a June 2026 deadline approaching on Russian oil transaction licenses, the coming weeks will test whether U.S. mediation can regain momentum, or whether the window for a negotiated settlement continues to narrow.

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