The announcement appears to preclude any kind of top-level meeting or breakthrough ahead of the 50-day deadline for an agreement given by President Donald Trump.

Ukrainian and Russian officials ended their third round of peace negotiations in under an hour Wednesday — falling short of establishing a cease-fire but agreeing to a prison swap. The talks took place in Istanbul just over a week after President Trump threatened Russian President Vladimir Putin with “very severe tariffs” if he doesn’t commit to a cease-fire in Ukraine within 50 days.

Russian and Ukrainian negotiators will meet in Istanbul on Wednesday evening for their first peace talks in more than seven weeks, with Moscow under pressure from U.S. President Donald Trump to strike a deal or face tough new sanctions.