What was the U.S. proposal regarding Ukraine's mineral resources and why was it rejected?

The U.S. proposed acquiring 50% of Ukraine's mineral wealth, including oil and gas resources, as a form of reimbursement for the billions invested in supporting Ukraine during the war. U.S. National Security Adviser Mike Waltz characterized it as American people deserving 'some kind of payback' for their investment in the conflict. President Zelensky ultimately rejected this proposal because it lacked security guarantees for Ukraine. While Ukrainian officials noted one potential benefit would be reinvesting profits into post-war reconstruction, these assurances were insufficient without explicit security commitments, leading to Ukraine's refusal of the deal.