Russia and Ukraine exchanged prisoners of war under the age of 25 on Monday in emotional homecoming scenes, the first step in a series of planned prisoner swaps that could become the biggest of the war so far.

Russia and Ukraine exchanged the first soldiers in a swap of POWs under the age of 26. Both sides shared videos on social media showing the freed servicemen, but the exact number of prisoners exchanged on Monday remains unclear.

A new prisoner swap between Ukraine and Russia has begun, officials in both countries said Monday, with Ukrainian soldiers who have spent nearly the entire duration of the war in captivity among those returning home.