The Ukrainian leader cast doubt on a meeting with Trump in Washington this week, and said he had several questions for the president.

The United States and Ukraine are trying to hammer out a natural resources agreement that would give Washington access to Kyiv’s untapped mineral riches in exchange for investments and what Ukraine hopes would be concrete security guarantees.

Trump has framed the emerging deal that would give the US access to Ukraine’s deposits of rare earth minerals as a chance for Kyiv to pay back the US for aid already sent.