By Erin Banco, Gram Slattery and Humeyra Pamuk WASHINGTON/RIYADH/ANTALYA, Turkey (Reuters) - U.S. President Donald Trump's senior envoys Steve Witkoff and Keith Kellogg will travel to Istanbul for potential talks on Thursday on how to end the war in Ukraine,

Ukrainian officials say Russia launched more than 100 drones, rejecting calls for a ceasefire as Zelenskyy says he'll "be waiting for Putin" to join him for direct talks in Turkey.

"We are waiting for (Russian President Vladimir) Putin's agreement and we agree that if there is no real progress this week, we want to work together at European level for a significant tightening of sanctions," Merz said at a news conference with his Greek counterpart.

A leading economist has been telling EU finance ministers that Russia’s economy is under growing strain as its invasion of Ukraine drags on.

For about 30 hours, the illusion of transatlantic unity over Ukraine was maintained. But US President Donald Trump’s response to a proposal from Russia’s Vladimir Putin shattered that.

U.S. President Donald Trump's senior envoys Steve Witkoff and Keith Kellogg will travel to Istanbul for potential talks on Thursday on how to end Russia's war in Ukraine, three sources familiar with the plans said on Tuesday.

A Ukrainian military spokesperson said the deployment signals that Russian forces are facing some trouble in Chasiv Yar.