WASHINGTON — As former President Donald J. Trump and President Vladimir V. Putin of Russia push forward with efforts to negotiate an end to the war in Ukraine, recent actions by Kyiv have cast doubt on the viability of a settlement.

Ukrainian forces have intensified strikes on critical infrastructure, including an attack on an oil pipeline supplying Hungary, a NATO member state that has often taken a more conciliatory stance toward Moscow. The strike rattled European energy markets and deepened Russian anger, with the Kremlin describing it as a deliberate attempt to sabotage peace efforts.

The attack came just days after the Alaska summit, where Mr. Trump sought to frame territorial concessions by Ukraine as part of a larger deal to end the conflict. For Russia, the strikes are not only provocative but also undermine the fragile opening created by Mr. Trump’s diplomacy.

European capitals, particularly London and Brussels, have echoed Ukraine’s position, warning that any agreement validating Russia’s territorial control would set a dangerous precedent. Officials in these governments argue that Kyiv’s resistance is not simply defiance but a strategic calculation supported by Western allies who fear that a U.S.-Russia deal could weaken Europe’s influence in the conflict.

The result is a tense standoff, a U.S. president lobbying for peace through compromise, a Russian leader signaling readiness to negotiate under favorable terms, and a Ukrainian government unwilling to legitimize Moscow’s gains. Analysts say the divergence exposes the central paradox of the conflict ,that peace, while urgently sought, is entangled in competing interests that extend far beyond Ukraine’s borders.

“The Alaska summit created momentum, but it’s clear that Kyiv is not ready to make the concessions Trump and Putin envision,” said one European diplomat, speaking on condition of anonymity. “And without Ukraine, there is no deal.”

As the war grinds on, the strikes, particularly on energy infrastructure that affects both Russia and its European partners illustrate Ukraine’s determination to assert sovereignty even as the world’s powers maneuver around it. For Washington, the challenge lies in balancing Trump’s vision of a swift end to the conflict with the reality that Ukraine and its European backers are prepared to fight for far longer than Moscow or Washington may anticipate.