WASHINGTON/KYIV - US National Security Adviser Mike Waltz on Thursday urged Ukrainian President Volodymyr Zelensky to "tone down" its stance and return negotiations over a minerals deal with the United States.

"They need to tone it down and take a hard look and sign that deal," Waltz told Fox News.

The proposed agreement, which reportedly demands a 50-percent share of Ukrainian natural resources, was initially presented by US Treasury Secretary Scott Bessent at the Munich Security Conference.

"You really need to sign this," Bessent reportedly told Zelensky during their meeting.

However, Kyiv has so far rejected the US proposal. "I can't sell our state," Zelensky said on Wednesday.

"In total, the United States separately gave us about $67 billion in weapons, and we received $31.5 billion in budget support," he said, adding: "But one cannot count up to 500 billion dollars and say, 'give us back 500 billion dollars in minerals,' that's not a serious discussion."

Despite this, the Ukrainian leader said Ukraine is grateful for the support and is open to discussing a deal that includes US security guarantees for his country.

Zelensky: Meeting with US envoy productive

Following a meeting in Kiev with Keith Kellogg, the US special envoy for Ukraine and Russia, Zelensky described their talks as "productive" in a post on the social platform X on Thursday.

"Ukraine is ready for a strong, effective investment and security agreement with the President of the United States. We have proposed the fastest and most constructive way to achieve results," he wrote.

"We had a detailed conversation about the battlefield situation, how to return our prisoners of war, and effective security guarantees," he said.

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Zelensky thanked the United States for the assistance and bipartisan support for Ukraine and voiced readiness to sign "a strong, effective investment and security agreement" with US President Donald Trump.

"We have proposed the fastest and most constructive way to achieve results," Zelensky emphasized.

According to Ukrainian presidential spokesperson Serhii Nikiforov, a joint press conference between Zelensky and Kellogg did not take place at the request of the US side.

Also on Thursday, Kellogg met with Ukrainian Foreign Minister Andrii Sybiha to discuss ways toward "comprehensive, just and lasting peace" in Ukraine.

After the meeting, Sybiha wrote on X that he affirmed Ukraine's willingness to achieve peace through strength and briefed Kellogg on Kiev's vision for the necessary steps.