It wasn’t enough to hijack a ceremony to honor Navajo code talkers so he could deride a U.S. senator as “Pocahontas.” President Trump now plans to go to Utah on Monday to decimate the Bears Ears National Monument, public land that’s sacred to five tribes of Native Americans.

Not content to relegate a historic figure to a partisan punch line, Trump is poised to build on a shameful legacy of betraying indigenous Americans. He is breaking a solemn promise to forever safeguard ancestral lands that speak to vital parts of our country’s history.

He reportedly intends to shrink the Bears Ears monument from more than one million acres to a mere 200,000 and to similarly gut the nearby Grand Staircase-Escalante National Monument. And he aims to expose hundreds of thousands of acres of these lands to destructive industrial mining and drilling that profit the few at the expense of the many.

That formula increasingly defines the Trump agenda. It strikes at the very ideals of equity and government by the people that sustain our notions of nationhood. In this case, it also revives an acutely painful injustice to the original American people. Wresting land from tribes was disgraceful in the 19th century. We’re not about to countenance it now.

During Monday’s White House ceremony to honor the heroism of the Navajo code talkers—who used their native language as the basis for a secret code that helped the U.S. Marines prevail in some of the bloodiest fighting in World War II—Trump used the occasion to scorn Senator Elizabeth Warren, calling her “Pocahontas." He managed in a single blundering stroke to offend the dignity of the event, mock Warren’s claim to Native American heritage, and belittle a woman of great importance in our nation’s history.

Tell Congress to stop Trump's assault on America's national monuments.