United States Secretary of State Antony J. Blinken has urged Nagorno-Karabakh parties to complete the exchange process for all prisoners of war.

Azerbaijan is still holding up to 300 Armenian prisoners of war, civilians and soldiers alike, while the Armenian side has returned all the POWs and detained persons, including two saboteurs who killed an Armenian minor and a serviceman a decade ago and were serving jail terms in Karabakh.

"The U.S. welcomes Azerbaijan's release of three Armenian detainees," Blinken said in a tweet on Wednesday, May 5, a day after a plane carrying the three Armenian prisoners of war landed in Yerevan.

"We call on both parties to fully and expeditiously complete the exchange process for all prisoners, detainees, and remains, and to respect their obligations to ensure the humane treatment of detainees."

19 of the hundreds of Armenian civilians and servicemen, who were taken captive by Azerbaijan during and after military hostilities in Artsakh (Nagorno-Karabakh), have been tortured and killed.