Patagonia, a maker of outdoor apparel and other gear known for its advocacy on environmental issues, is denouncing President Trump for his decision to shrink two national monuments in Utah.

"The President Stole Your Land," the company said in stark white lettering on a black background as part of an internet campaign aimed at fighting two White House proclamations to scale down the Bears Ears and Grand Staircase-Escalante monuments by hundreds of thousands of acres.

Yvon Chouinard, Patagonia's outspoken founder, also vowed to sue Mr. Trump in an interview with CNN yesterday.

"The administration's unlawful actions betray our shared responsibility to protect iconic places for future generations and represent the largest elimination of protected land in American history," Hilary Dessouky, Patagonia's general counsel, said in an e-mailed statement. "We worked to establish Bears Ears National Monument and will now fight to protect it. On Wednesday, we will be filing a lawsuit challenging the President's revocation of Bears Ears National Monument."

Chouinard and Patagonia have long been active on environmental, labor and other issues. Under the company's so-called one-percent program, Patagonia has gave away more than $75 million to at least 3,400 environmental organizations, according to a profile in the New Yorker last year.

Patagonia CEO Rose Marcario echoed Chouinard's comments in a statement on the company's website. And earlier this year, the company took out its first-ever television ad to protest the Trump administration's potential moves after he ordered a review of national monuments, according to online publication Retail Dive.

"The administration's unlawful actions betray our shared responsibility to protect iconic places for future generations and represent the largest elimination of protected land in American history," Marcario said in the statement. "We've fought to protect these places since we were founded and now we'll continue that fight in the courts."

Interior Secretary Ryan Zinke disputed the claim, calling it "nefarious, false and a lie" in a conference call Tuesday, and saying that the land targeted by Mr. Trump remains protected because it is still under federal control.

But the stand "seems highly consistent with Patagonia's values and those of its employees and customers," said Jerry Davis, a professor at the University of Michigan who has studied on activism and brands, in an email. "I do not see a lot of risk for a company like Patagonia -- a Certified B Corporation with a strong history of standing up for its values -- in speaking out against Trump's move."

Patagonia isn't alone in publicly protesting the move. Outdoor gear retailers REI and The North Face also released less strident statements protesting the announcement and directing customers on how to protest the move.

Earlier this year, the industry's largest outdoor gear show abandoned Salt Lake City in protest over the Trump administration's proposal to shrink the monuments. Executives from the top companies in the industry met earlier this year with the Outdoor Industries Association to discuss pulling out of Utah in protest, according to Outdoor Magazine, which also posted a recording of the conference call.