The mayor of Kyiv, Vitali Klitschko, has told the BBC that Ukraine may have to give up land as part of a peace deal with Russia.
It follows growing pressure from US President Donald Trump to accept territorial concessions.
The political opponent to Ukrainian President Volodymyr Zelensky, called it a "temporary" solution. But what might that actually mean?
BBC Verify's Merlyn Thomas explains.
Produced by Aisha Sembhi. Graphics by Sally Nicholls and Mark Edwards.