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.

Ukraine and Russia, earlier this month, agreed to exchange 1,000 prisoners of war and civilian detainees each in a rare moment of cooperation in more than three years of war.

The attacks came even as the two countries completed their biggest prisoner swap since Moscow launched its full-scale invasion in February 2022.

The massive missile and drone attack across Ukraine followed large strikes the night before, and casts more doubt on the U.S.-brokered peace process.

Russia and Ukraine have completed the first phase of what is expected to be the biggest prisoner exchange since the start of the war, with almost 800 people released on Friday.

Swiss authorities said on Sunday they were exploring whether to open a legal investigation into the activities of the Gaza Humanitarian Foundation, a U.S.-backed organisation that plans to oversee aid distribution in the Palestinian enclave.

Russia and Ukraine have exchanged hundreds more prisoners as part of a major swap that amounted to a rare moment of cooperation in otherwise failed efforts to reach a ceasefire.

Moscow’s battlefield edge is waning, experts say. But President Donald Trump seems disinclined to ramp up pressure on the Kremlin to end the war in Ukraine.