President Donald Trump referred to Massachusetts Sen. Elizabeth Warren as "Pocahontas" during a White House event Monday honoring Native American code talkers who served in World War II.

The President, standing beside three Najavo code talkers and a portrait of former president Andrew Jackson, made the comment in reference to Warren's heritage, which the Democrat Senator on numerous occasions has said has Native American roots.

"You were here long before any of us were here," Trump said to the veterans in the Oval Office. "Although we have a representative in Congress who they say was here a long time ago. They call her Pocahontas."

This is not the first time Trump has called Warren, one of his most vocal critics, "Pocahontas." He frequently called her that throughout his presidential campaign and claimed that she was lying about her genealogy, saying it was "racist" and that she should be fact-checked.

White House press secretary Sarah Huckabee Sanders doubled down on that sentiment at Monday's briefing.

"I think what most people find offensive is Senator Warren lying about her heritage to advance her career," Sanders told reporters, adding that she didn't consider the label "Pocahontas" a racial slur.

Warren herself additionally responded to Trump's dig, telling MSNBC , "It was deeply unfortunate that the President of the United States cannot even make it through a ceremony honoring these heroes without throwing out a racial slur."

John Norwood, general secretary for the Alliance of Colonial Era Tribes, told NBC that Trump's remark "smacks of racism" and that he should "stop using our historical people of significance as a racial slur against one of his opponents."

The Navajo code talkers used their native language to outwit U.S. enemies and exchange classified military information throughout both World Wars.

Following his "Pocahontas" comment, Trump said: "But you know what? I like you, because you are special."