Patagonia, an American outdoor clothing and gear retailer, slammed President Donald Trump after he announced plans to shrink the size of two national monuments.

The California-based company on Monday modified its homepage to initially display a black screen with the message "The President Stole Your Land" to rally the public into joining its cause which, according to some local media reports, includes a possible legal action against Trump.

"In an illegal move, the president just reduced the size of Bears Ears and Grand Staircase-Escalante National Monuments. This is the largest elimination of protected land in American history," Patagonia said on its website.

The White House released a statement on Monday detailing Trump's plans to reduce the size of two national monuments in Utah — undoing such land protections for the first time in 50 years, according to the Associated Press.

Bears Ears and Grand Staircase-Escalante sit on millions of acres of land.

Bears Ears, created last December by President Barack Obama, will be reduced by about 85 percent, to 201,876 acres (315 square miles). Grand Staircase-Escalante, designated in 1996 by President Bill Clinton, will be reduced from nearly 1.9 million acres (nearly 3,000 square miles) to 1,003,863 acres (1,569 square miles), the AP reported.