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.

CHERNIHIV REGION, Ukraine (AP) — An exchange of prisoners between Russia and Ukraine from their more than three-year war was underway Friday, a senior Ukrainian official said. The swap was not yet finished, according to the official, who spoke on condition of anonymity because he was not authorized to speak publicly.

Many Russian soldiers say they would see a cease-fire along the current front lines as a failure, hinting at the nationalist discontent the Kremlin could face in accepting a cease-fire.

Russian armed forces are creating a “security buffer zone” along the border between Russia and Ukraine, President Vladimir Putin said Thursday.

Russian forces in Ukraine have made only small territorial gains this year amid steady resistance from Kyiv’s military, undercutting President Vladimir Putin’s assertions that his army has gained the upper hand in the war.

Russian President Vladimir Putin wants to boost Russian arms exports to other countries. "It is necessary to actively increase the volume of export deliveries," he said in a speech broadcast on state television on Friday.

By Dmitry Antonov MOSCOW (Reuters) -Russian Foreign Minister Sergei Lavrov cast doubt on Friday over the Vatican as a potential location for peace talks between Russia and Ukraine, saying that the Holy See itself would find it uncomfortable to host two mainly Orthodox Christian nations.