Corrections & Clarifications: This story has been updated to clarify the original description of Nathan Phillips’ military service. Phillips is a Vietnam-era veteran who served in the U.S. Marine Corps Reserve from May 1972 to May 1976 and did not deploy to a war zone, according to the Defense Department.

CINCINNATI – A Catholic high school in Kentucky apologized Saturday after backlash arose on social media as a widely shared video showed a group of young men surrounding indigenous marchers in Washington, D.C.

The video shows a young man wearing a "Make America Great Again" cap standing near and staring at a man who is drumming as other young men surrounding them cheer and chant. Some of the onlookers appear to wear clothing bearing insignia from Covington Catholic High School in Park Hills, Kentucky.

The indigenous man holding a drum was participating in an Indigenous Peoples March and was later identified as Nathan Phillips, a Marine Corps veteran and Native American elder of the Omaha tribe, by Indian Country Today.

In a joint statement Saturday, the school and Diocese of Covington said they were reviewing the incident and they would "take appropriate action, up to and including expulsion."

"We condemn the actions of the Covington Catholic High School students towards Nathan Phillips specifically, and Native Americans in general, Jan. 18, after the March for Life, in Washington, D.C. We extend our deepest apologies to Mr. Phillips. This behavior is opposed to the Church’s teachings on the dignity and respect of the human person," the statement read.

People across social media platforms condemned the incident as an attempt by the group of young men to intimidate the marchers and had called for a response from the school.

Covington Catholic's website said students planned to attend the March for Life event, held Friday in Washington, D.C., the same day as the Indigenous Peoples March.

"We know this incident also has tainted the entire witness of the March for Life and express our most sincere apologies to all those who attended the March and all those who support the pro-life movement," the school and diocese also said in their statement Saturday.

The uproar spread on social media Saturday morning, as millions viewed videos from the scene.

The journalist who identified the elder as Phillips, Vincent Schilling, spoke to The Enquirer by phone Saturday.

Schilling, a member of the Mohawk tribe and a veteran himself, said he participated in a ceremony about two years ago alongside Phillips to honor Native American veterans at Arlington National Cemetery.

"As a Native American journalist, I find this to be one of the most egregious displays of naïve – I can’t even say naïve. It’s racism. It’s blatant racism," Schilling said.

Schilling added that Phillips has been harassed in the past. A Fox affiliate in Detroit reported in 2015 that students at Eastern Michigan University lobbed racist slurs at him.

"The guy has just been through a lot," Schilling said.

Schilling added that, as a member of the Mohawk tribe, deference for elders is a respected ideal.

"To see Mr. Phillips treated this way is an incalculable amount of disrespect, and it's absolutely unacceptable in Native culture," he said.

Phillips was singing a song about indigenous peoples' activism and autonomy, Schilling said.

"The thing that’s sad about all of this is it’s not surprising," Schilling said. "Because as a Native man, I’ve got it countless times myself I’ve been mocked, I’ve been teased, my culture has been ridiculed. This is just another brick in the wall."

About 140,000 living Native Americans are veterans, according to the Smithsonian National Museum of the American Indian.

Rep. Deb Haaland of New Mexico, one of the first two Native American congresswomen, tweeted about the elder on Saturday.

A video interview of the man included in the thread that Haaland retweeted was shot by Kaya Taitano, a Chamoru activist from Guam.

Taitono shared with The Enquirer an extended version of the shorter video that has gone viral.

In the video, the man identified as Phillips says he heard chants of "build that wall, build that wall," during the incident.

"This is indigenous lands. We're not supposed to have walls here. We never did for millennia, before anyone else came here, we never had walls, we never had a prison," he said. "We always took care of our elders, we took care of our children. ... We taught them right from wrong."

In the extended version of the video, the man looks down and sighs.

"Maybe all of us that are on this Mall here tonight, our relatives seven generations (from now) will come back here and say something good happened here," he said.

Covington Catholic's Twitter, Facebook and Instagram accounts have been made private, preventing public view of those accounts' content.

The high school, about 5 miles south of Cincinnati, is a private, all-boys school with about 550 students, according to privateschoolreview.com.

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