Native American leaders fired back at President Donald Trump’s reference to Sen. Elizabeth Warren (D-Mass.) as “Pocahontas” by calling the term an “unnecessary” ethnic slur.

Trump, who has identified Warren as “Pocahontas” before, made the remark during a ceremony Monday recognizing Native American code talkers who served during World War II.

“This was a day to honor them and to insert something like that, that belongs on the campaign trail, it doesn’t belong in the room when our war heroes are being honored,” Navajo Nation President Russell Begaye told CNN’s “New Day” on Tuesday. Navajo Nation Council Delegate Amber Kanazbah Crotty on Monday called Trump’s comment “deeply offensive and dangerous.”

Navajo Nation President Russell Begaye: Trump's "Pocahontas" remark "unnecessary and culturally insensitive" https://t.co/qv4zEElHp7 — New Day (@NewDay) November 28, 2017

Begaye said Trump’s remark was “uncalled for.” When anchor Alisyn Camerota asked whether it amounted to an ethnic slur, he said yes.

“Pocahontas is a real person, not something that’s just made up,” Begaye continued. “This is a young lady, a Native American woman that played a critical role in the life of this nation, and to use that person in that way is unnecessary and is being culturally insensitive.”

Other Native American organizations issued even more strongly worded statements.

The Alliance of Colonial Era Tribes asked Trump on Monday to “stop using our historical people of significance as a racial slur against one of his opponents.”

“The reference is using a historic American Indian figure as a derogatory insult and that’s insulting to all American Indians,” the group’s general secretary, John Norwood, said.

The National Congress of American Indians “cannot and will not stand silent when our Native ancestors, cultures and histories are used in a derogatory manner for political gain,” said its executive director, Jacqueline Pata.