Russian President Vladimir Putin has said that he wants to seize the entire region, parts of which Kyiv’s forces still hold. Zelenskyy has ruled out ceding this territory, arguing that Putin could use it as a base to again attack Ukraine. Russia currently occupies about one-fifth of Ukraine’s territory.

Secretary Marco Rubio warned Thursday that stalemates are “very dangerous” because they either end in a negotiated settlement or escalation. In the context of Ukraine that “could wind up being a sabotage campaign in neighboring countries that are members of NATO,” he said.

European leaders are growing increasingly concerned about Russia escalating and expanding the conflict onto the continent.

“In the end, we do not believe that there is a military solution to this conflict, to this war, we think this war needs to end in a negotiated settlement,” Rubio said. “The sooner, the better.”

In separate comments to Greek newspaper Kathimerini, Rubio said “there don’t seem to be prospects of a negotiated settlement” on peace in Ukraine right now. Kremlin spokesperson Dmitry Peskov responded by saying he agreed with the secretary’s assessment, Russian state news agency Tass reported.

The U.S. diplomatic efforts to end the war were revived last month when Witkoff and Kushner travelled to Moscow and, for the first time, Kyiv. No major breakthroughs were announced.

The White House has previously repeated some of Putin’s hardlines demands and tried to push Kyiv for concessions.

Putin explained the invasion by saying Russia was trying to demilitarize Ukraine, and overthrow what he called Kyiv’s “Nazi ideology” driven government — a common Kremlin propaganda line.

What was supposed to be a swift military operation to topple Zelenskyy and replace him with a pro-Kremlin government quickly foundered, leaving the capture of Donbas as his only option to claim a significant victory in Ukraine.