Ukraine on Saturday was seriously considering a revised American proposal for its vast natural resources that contains virtually the same provisions that Kyiv previously rejected as too onerous, according to a draft document of the new proposal.

Some of the terms appear even tougher than in a previous draft.

The proposed agreement would significantly shift onto a mercantile footing the United States’ three-year alliance with Ukraine in the largest war in Europe since World War II. The conflict to date has largely been seen as a struggle to secure Ukraine and the European continent from an authoritarian threat from Russia.

The Trump administration’s terms could also strip Ukraine of funds that are now mostly invested in the country’s military and defense industry, and that could help rebuild the country once the war is over.

The terms of the new proposal, which is dated Feb. 21 and was reviewed by The New York Times, call for Ukraine to relinquish half of its revenues from natural resources, including minerals, gas and oil, as well as earnings from ports and other infrastructure. A similar demand was made in a previous version of the deal, dated Feb. 14 and reviewed by The Times.

Ukraine had been floating the prospect of a partnership with the United States on its valuable natural resources as a way to persuade Mr. Trump to provide additional support for its war effort. President Volodymyr Zelensky had also been seeking security guarantees for Ukraine, a condition that was absent in the first draft agreement presented to him last week, prompting him to decline to sign the deal.

But while the new document calls for a series of commitments from Ukraine it still does not provide any specific commitments in return from the U.S. to help Ukraine sustain its war effort. It says, however, that the United States intends to provide a long-term financial commitment to help Ukraine develop economically.

The new document states that revenues from Ukraine’s resources will be directed to a fund in which the United States holds 100 percent financial interest, and that Ukraine should contribute to the fund until it reaches $500 billion — the amount Mr. Trump has demanded from the war-torn country in exchange for American aid.

That figure far exceeds the country’s actual revenues from resources, which were $1.1 billion last year, and more than four times the value of U.S. aid committed to Ukraine so far. The $500 billion sum was not mentioned in the previous version of the deal, though Mr. Trump had said publicly that was what he wanted.

It is unclear whether Mr. Trump wants it in exchange for past American military and financial assistance, or whether it would also apply to future support.

Ukraine has not said whether it would agree to the deal under the proposed terms. Ruslan Stefanchuk, the speaker of Ukraine’s Parliament, told local media that a government-level group would begin working on the agreement on Monday and that Ukraine wanted to receive specific security guarantees in exchange for access to its resources.

Ukraine has tried to resist a total capitulation to American demands on natural resources, but has faced intense pressure from President Trump, who views access to Ukraine’s vast mineral wealth as necessary repayment for the billions the United States has provided Kyiv for its war against Russia.

The document suggests the United States may send more aid to Ukraine in the future — but at a high price. It states that Ukraine will be required to contribute to the fund a sum equal to twice the amount the United States might give to Ukraine after the deal is signed.

The revised proposal states that the United States could reinvest a portion of the revenue into Ukraine’s postwar reconstruction, including by investing in the development of the country’s subsoil assets and infrastructure.

The new draft agreement also includes provisions for revenues from territories currently occupied by Russia, in the event they were freed: The share of resource revenues contributed to the fund from liberated areas would be 66 percent. Russia currently occupies about a fifth of Ukraine’s territory, including significant portions of the resource-rich Donbas region.

The document reviewed by The Times outlines the establishment of a fund to receive revenues from resource extraction and other sources. A second agreement, described as the Fund Agreement, would be concluded later to work out specific details.

Keith Kellogg, Mr. Trump’s special envoy to Ukraine and Russia, visited Kyiv from Wednesday to Friday and discussed the new proposal with Mr. Zelensky. Treasury Secretary Scott Bessent first met with Mr. Zelensky recently to discuss the deal, and more recently Mr. Trump’s commerce secretary, Howard Lutnick, became involved the negotiations, according to a person familiarly with the discussion.

A potential deal for Ukraine’s resources has been a major point of dispute in a rapidly deteriorating relationship between Mr. Zelensky and Mr. Trump. Their interactions became acrimonious in the last week as the American president assailed Mr. Zelensky in highly personal terms, calling him “an unelected dictator.”

The Ukrainian president, in turn, said that Mr. Trump was living in a “disinformation web” after Mr. Trump falsely claimed that Ukraine had started the war against Russia.

Mr. Zelensky’s initial hesitancy, and comments that were perceived by Mr. Trump and cabinet officials as public criticism of the president prompted a fierce backlash from the Trump administration. That possibly led to the addition of further demands written into the agreement, according to drafts and people familiar with the discussions of the deal on the Ukrainian side.

Two of the people who had the new proposal described to them said that one of the few changes made by the United States that could satisfy Ukraine was the removal of a clause placing the deal under the jurisdiction of a New York court. The provision had raised concerns on the Ukrainian side, because it could weaken Ukraine’s legal standing in case of a dispute.

Whether Ukraine can meet the terms requested by the Trump administration is unclear.

Ukraine is not a major natural resource exporting country, as the most dynamic spheres of its economy have been agriculture, steel and other metal smelting and outsourced programming work for Silicon Valley companies. Revenues from natural resources comprised 2.5 percent of budget revenue last year.

Ukrainian officials and energy experts also say that any new fields would likely take years and significant investment to develop. Much exploration remains to be done to assess the true value of the country’s critical minerals, they say, and administrative and legislative obstacles still hinder foreign investment in the sector.

The Trump administration has suggested that the mere presence of American economic interests in Ukraine would be a security guarantee for Kyiv. Top U.S. cabinet members have pressed Mr. Zelensky to sign the deal in recent days.

“President Zelensky is going to sign that deal, and you will see that in the very short term,” the U.S. national security adviser, Mike Waltz, said on Friday. “And that is good for Ukraine. What better could you have for Ukraine than to be in an economic partnership with the United States?”

Speaking in the Oval Office later Friday, Mr. Trump said, “We’re going to either sign a deal, or there’s going to be a lot of problems with them.”

Maggie Haberman contributed reporting.