Ukrainian President Volodymyr Zelensky said any constitutional changes that relate to security guarantees in the country would need to be decided through a referendum and not by him alone.
The President made the comments during an interview with Ukraine's public broadcaster Suspilne News on Monday.
"It is a long process which will be decided by the parliament and by the Ukrainian people," he said.
Some context: It comes as delegates from Ukraine and Russia have held a series of peace talks. Zelensky said he has not met with Russian negotiators but told his delegation that any significant compromise would require a referendum.
"I explained to our negotiators at the talks that when one is talking about changes — and these changes may be of historic importance — there is no other way around it, we will have to hold a referendum," he said.
"The people will have to speak up and respond to this or that form of compromise you have mentioned. And what they (the compromises) will be is the subject of our talks and understanding between Ukraine and Russia."
When a Suspilne reporter asked about the limit of the compromise Ukraine would go for, Zelensky said: "I think that without this meeting you cannot truly understand what they are really prepared to do in order to stop the war and what they are prepared to do if we are not ready for this or that compromise."
Zelensky repeated previous comments that he was ready to meet with Russian President Vladimir Putin.
"The issue of the occupied territories is important for us. But I am certain that a solution will not come at this meeting," he said.
Here's the background to the "occupied territories:" In early 2014, mass protests in Kyiv known as Euromaidan forced out a Russia-friendly president after he refused to sign an EU association agreement. Russia responded by annexing the Ukrainian peninsula of Crimea and fomenting a separatist rebellion in Ukraine's east, which seized control of part of the Donbas region. In late February ahead of the invasion, Putin recognized the two separatist territories in eastern Ukraine as independent states.