Joe Biden gave an unexpected response to a protester who said his friends died in combat in Syria

AP Photo/Manuel Balce Ceneta

Joe Biden.

While campaigning for Hillary Clinton in Ohio on Thursday, Vice President Joe Biden was interrupted by a protester who repeatedly shouted at him about friends he said were killed during a combat mission in Syria.

"Some of my friends, my American friends died," the protester said. "Why did you tell the YPG to go back across the border," the man shouted, referring to a mission to liberate the Syrian city of Manbij.

The crowd attempted to shout the man down, but Biden addressed him directly.

"Because the deal was to get them into Manbij and to work they had to go back across the Euphrates so we could have special forces move in that's why," Biden explained.

As the man continued to lament that his comrades died, Biden said, "So did my son."

Biden's son, Beau, served in the United States Army for nearly 15 years. He died in 2015 after a long battle with brain cancer.

Watch the exchange between Biden and the protester below: