Russian President Vladimir Putin said Thursday that he agrees in principle with a U.S. proposal for a 30-day ceasefire in Ukraine, but he emphasized that the terms are yet to be worked out and added that any truce should pave the way to lasting peace.

“The idea itself is correct, and we certainly support it,” Putin told a news conference in Moscow. “But there are issues that we need to discuss, and I think that we need to talk about it with our American colleagues and partners and, perhaps, have a call with President Trump and discuss it with him.”