Russia and Ukraine have swapped hundreds more prisoners of war, the third and last part of a major swap, hours after a massive attack by Moscow, killing at least 12.

The attack came on the third day of a planned prisoner swap between Russia and Ukraine, the only tangible outcome from peace talks in Istanbul earlier this month.

The missile and drone attack casts more doubt on the U.S.-brokered peace process. President Volodymyr Zelensky condemned the “silence of America and others around the world.”