ISTANBUL 

US President Donald Trump is actively pursuing a face-to-face meeting with Russian President Vladimir Putin to advance Ukraine peace efforts "as soon as feasible," US Secretary of State Marco Rubio said in an interview set to be aired on Sunday on CBS News' Face the Nation.

"The president wants to do it. He wants to do it as soon as feasible," Rubio told host Margaret Brennan, adding that such high-level engagement might represent the only path through solving the Russia-Ukraine war.

"One of the things that could help break this logjam, perhaps the only thing that can, is a direct conversation between President Trump and Vladimir Putin," Rubio said.

He confirmed the administration has already extended a formal invitation, though logistics remain unfinalized.

"The mechanics of setting that kind of meeting up would require a little bit of work, so I can't say that's being planned as we speak in terms of picking a site and a date," he explained.

This initiative comes following peace talks in Istanbul on Friday alongside other diplomatic developments, including the Vatican's offer to host Russia-Ukraine negotiations at various levels.

Rubio noted the Kremlin has expressed conditional openness to such Vatican-hosted talks.

Rubio said he talked with Russian Foreign Minister Sergey Lavrov to assess recent negotiations in Istanbul. He said the talks "were not a complete waste of time" and reported two tangible outcomes: an agreement for a 1,000-prisoner exchange from each side, which he called "very positive" from a humanitarian perspective, and Russia's preparation of a document outlining ceasefire requirements.

The Trump administration is carefully evaluating Russian sincerity, Rubio indicated. "If those papers have ideas on them that are realistic and rational, then I think we know we've made progress," he said, while warning that "endless talks" without substantive proposals may result in the US having​​​​​​​ "a different assessment."

On Iran's nuclear program, Rubio said unequivocally: "Iran can never have a nuclear weapon."

​​​​​​​​​​​​​​He highlighted that any uranium enrichment capability can quickly lead to weapons-grade material.

"The president's preference is to achieve that through a peaceful negotiation. In fact, the president's preference is not only that Iran not pursue nuclear weapons, but that Iran be a rich, peaceful and prosperous country where its people can be happy. He wants them to have a better future," Rubio said.