“We are working to implement some ideas in connection with the Ukrainian settlement. This work is ongoing,” Dmitry Peskov said in a conference call with reporters.

“There is nothing concrete yet that we could and should announce. This is a drawn-out process because of the difficulty of its substance,” the Kremlin spokesman said when asked about Trump’s anger at Russian President Vladimir Putin’s comments dismissing Ukrainian President Volodymyr Zelenskyy’s legitimacy to negotiate a deal.

Russia has effectively rejected a U.S. proposal for a full and immediate 30-day halt in the fighting. The feasibility of a partial ceasefire on the Black Sea, used by both countries to transport shipments of grain and other cargo, was cast into doubt after Kremlin negotiators imposed far-reaching conditions.

Trump promised during last year’s U.S. election campaign that he would bring Europe’s biggest conflict since World War II to a swift conclusion.

Peskov didn’t directly address Trump’s criticism of Putin on Sunday, when he said he was “angry, pissed off” that Putin had questioned Zelenskyy’s credibility as leader.

But the spokesman said that Putin “remains absolutely open to contacts” with the U.S. president and was ready to speak to him.

Both countries are preparing for a spring-summer campaign on the battlefield, analysts and Ukrainian and Western officials say.

Putin on Monday ordered a regular bi-annual call-up intended to draft 160,000 conscripts for an one-year tour of compulsory military service. Russian authorities say that the troops deployed to Ukraine only include volunteers who signed contracts with the military and conscripts aren’t sent to the frontline. Some draftees, however, fought and were taken prisoners when the Ukrainian military launched an incursion into Russia’s Kursk region in August.

Zelenskyy said late Sunday that there has been no reduction in Russia’s attacks as it drives on with its invasion of Ukraine that began in February 2022.

“The geography and brutality of Russian strikes, not just occasionally, but literally every day and night, show that Putin couldn’t care less about diplomacy,” Zelenskyy said in his daily address.

“And almost every day, in response to this proposal, there are Russian drones, bombs, artillery shelling, and ballistic strikes,” he said.

He urged further international pressure on Moscow to compel Russia to negotiate, including new sanctions.

The European Union’s foreign policy chief Kaja Kallas picked up on that theme at a meeting of some of the bloc’s top diplomats in Madrid on Monday.

“Russia is playing games and not really wanting peace,” Kallas told reporters ahead of the meeting, which was due to discuss the war. “So our question is, how can we put more pressure on Russia.”

Trump said he would consider imposing further sanctions on Russia, which already faces steep financial penalties, and using tariffs to undermine its oil exports.

Kharkiv, Ukraine’s second-largest city, came under another Russian drone attack overnight, injuring three people, the Ukrainian Interior Ministry said Monday.

Russia also fired two ballistic missiles and 131 Shahed and decoy drones, the Ukrainian air force said.

Meanwhile, Russia’s Defense Ministry said air defenses shot down 66 Ukrainian drones early Monday over three Russian regions.

“The continuing attacks by the Ukrainian armed forces on Russia’s energy facilities show the complete lack of respect for any obligations related to the settlement of the conflict in Ukraine by the Kyiv regime,” the ministry said in a statement.