The United States will share future revenues from Ukraine’s mineral reserves under a deal announced by the Trump administration on Wednesday that creates a joint investment fund between the countries.

The agreement comes after months of fraught negotiations as the United States tries to broker an end to Ukraine’s three-year war with Russia. It is intended to give President Trump a personal stake in the country’s fate while addressing his concerns that the United States has provided Kyiv with a blank check to try to withstand Russia’s invasion.

“This agreement signals clearly to Russia that the Trump administration is committed to a peace process centered on a free, sovereign and prosperous Ukraine over the long term,” Treasury Secretary Scott Bessent said in a statement. “President Trump envisioned this partnership between the American people and the Ukrainian people to show both sides’ commitment to lasting peace and prosperity in Ukraine.”

He added: “And to be clear, no state or person who financed or supplied the Russian war machine will be allowed to benefit from the reconstruction of Ukraine.”

The Trump administration did not immediately provide details about the agreement, and it was not clear what it meant for the future of American military support for Ukraine. One person familiar with the negotiations, discussing them on the condition of anonymity, said the final deal does not include explicit guarantees of future U.S. security assistance. Another said the United States rejected that idea early in the process. Despite the fanfare, the deal will have little significance if fighting between Ukraine and Russia persists.

But Ukraine’s supporters hope the agreement might lead Mr. Trump to see the country as something more than a money pit and an obstacle to improved relations with President Vladimir V. Putin of Russia.