Kaine says US troops killed in Niger were on unauthorized mission

Kaine, who sits on the Senate Armed Services Committee and the Foreign Relations Committee, told CNN's "New Day" that during a briefing Tuesday, he and other senators learned that the troops initially attempted to embark on a search for a high value target, a mission they were not authorized, trained or equipped to conduct. They later reverted to an advisory capacity with the Nigerien forces they were working with.

"I believe that the troops who were sadly killed in Niger in October of 2017 were engaged in a mission that they were not authorized by law to participate in and that they were not trained to participate in. And that is a significant reason that they tragically lost their lives," he added.

Kaine refrained from further details about the mission because of classified nature of the briefing.

The Virginia senator told CNN that other senators left the briefing "somewhat shocked."

"After the hearing yesterday we had huddled. We are going to figure out a way that the story will be told and that people will be held accountable," he added.

The team that was attacked in Niger was given several different tasks before it was ambushed, but its primary mission was to advise and assist a unit of 30 Nigerien soldiers.

The team advising the support units was assigned to visit the abandoned encampment to collect intelligence on the suspect. They did not encounter any enemy forces at the site and left the location.

On their way back to base, they stopped in a separate village in order to enable the Nigerien troops to replenish supplies. While there, US troops met with local leaders as a courtesy.

The US officials said it was "quite probable" that someone in the village tipped off the ISIS-affiliated terrorists that US forces were in the village, setting up the ambush.