The announcement follows mounting fears that the two nuclear-armed countries were on the brink of engaging in another full-scale war.

"We agreed that a full and unconditional ceasefire must begin on Monday, May 12, for at least 30 days. We jointly demand this from Russia, and we know we are supported in this by the United States," Zelensky said.

Ukrainian media outlet ZN.UA reported on May 10 that their law enforcement sources confirmed an ongoing probe by the National Anti-Corruption Bureau into suspected embezzlement, money laundering and bribery.

Iran is preparing to send Russia Fath-360 short-range ballistic missile launchers, Reuters reported on May 9, citing Western security and regional officials familiar with the matter.

"Ukraine and all allies are ready for a complete unconditional ceasefire on land, in the air, and at sea for at least 30 days, starting as early as Monday," Ukraine's Foreign Minister Andrii Sybiha wrote.

U.S. President Donald Trump has acknowledged in private that Russia is difficult to negotiate with because they "want the whole thing," referring to Ukraine, the WSJ reported, citing sources familiar with the comments.

The visit marks Merz’s first trip to Ukraine, and the first time all four leaders have travelled there together.

A notice about the airspace closure was published on the U.S. Defense Department's NOTAM (Notice to Airmen) website on May 10, as cited by Ukrainian defense news outlet Militarnyi.

"As in the past, it is now for Russia to show its willingness to achieve peace," the EU's statement reads.

Kremlin spokesperson Dmitry Peskov rejected the idea of a 30-day ceasefire between Russia and Ukraine, claiming in an interview with ABC News on May 10 that it would be "an advantage" for Ukraine.

"Our involvement in the war was justifiable, and this belongs to our sovereign rights," North Korean dictator Kim Jong Un said. "I regard this as part of the sacred mission we must execute for our brothers and comrades-in-arms."

The number includes 1,310 casualties that Russian forces suffered over the past day.

"We have a plan B and a plan C. But our focus is plan A, the essence of which is to get everyone's support" for Ukraine's accession, EU foreign policy chief Kaja Kallas said.