Russia’s economy is under growing strain as its invasion of Ukraine drags on and Western sanctions are undermining President Vladimir Putin’s ability to sustain his war, a leading European economist said after briefing finance ministers on Tuesday.

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 Russia's war in Ukraine,

"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.

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.

The announcement was made by leaders of Britain, France, Germany, Poland and Ukraine after a meeting in Kyiv, and a phone call with President Trump.

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

Russia has spent most of its National Wealth Fund in the past few years, with liquid funds potentially being depleted in 2025, one economist says.