Secretary of State John Kerry said Friday that the U.S. would impose sanctions over a planned referendum in the Crimean region to secede from Ukraine, conceding that Russian President Vladimir Putin would not change his position before Sunday’s vote.

“If the referendum takes place there will be some sanctions,” Kerry told reporters after six hours of talks with Russian Foreign Minister Sergey Lavrov that failed to resolve the crisis. “There will be some response, let me put it that way.”