President Joe Biden on Sunday appeared at Dover Air Force Base in Delaware to participate in the "dignified transfer" of the 13 service members killed in the recent Kabul airport terrorist attacks.

First lady Jill Biden, Secretary of State Antony Blinken, Secretary of Defense Lloyd Austin and several civilian and uniformed military leaders also attended the somber event, which involved caskets draped in the American flags. They were carried out of the C-17 military transport plane into black vans by pallbearers, the family members observed from a private area.

The Bidens met with the servicemen's families, who were in attendance but not filmed or photographed by the media, according to the White House.

President Biden called the servicemen "the spine of America," while also addressing retribution efforts for the attacks in Kabul, Afghanistan.

"We will hunt you down and make you pay," Biden said.

The service members were guarding the Kabul airport in order for Americans and Afghan refugees to evacuate when a self-proclaimed Islamic State terror group that is against the Taliban performed a suicide attack.

The service members killed were: Army Staff Sgt. Ryan Knauss, Marine Staff Sgt. Darin Hoover, Marine Sgt. Johanny Rosariopichardo, Marine Sgt. Nicole Gee, Marine Cpl. Daegan Page, Marine Cpl. Humberto Sanchez, Marine Lance Cpl. David Espinoza, Marine Lance Cpl. Jared Schmitz, Marine Lance Cpl. Dylan Merola, Marine Lance Cpl. Kareem Nikoui and Navy Hospitalman Maxton Soviak.