WASHINGTON (AP) — Interior Secretary Ryan Zinke is recommending that four large national monuments in the West be reduced in size, potentially opening up hundreds of thousand or even millions of acres of land revered for natural beauty and historical significance to mining, logging and other development.

Zinke’s recommendation, revealed in a leaked memo submitted to the White House, prompted an outcry from environmental groups who promised to take the Trump administration to court to block the moves.

The Interior secretary’s plan would scale back two huge Utah monuments — Bears Ears and Grand Staircase-Escalante — along with Nevada’s Gold Butte and Oregon’s Cascade-Siskiyou. More logging and other development also would be allowed at three other monuments — two in in New Mexico and one in Maine.

Bears Ears, designated for federal protection by former President Barack Obama, totals 1.3 million acres in southeastern Utah on land that is sacred to Native Americans and home to tens of thousands of archaeological sites, including ancient cliff dwellings. Grand Staircase-Escalante, in southern Utah, includes nearly 1.9 million acres in a sweeping vista larger than the state of Delaware.

Grand Staircase has been a source of ire for local officials and Republican leaders for more than two decades amid complaints that its 1996 designation as a monument by former President Bill Clinton closed off too much land to development.

Cascade-Siskiyou, in southwestern Oregon, protects about 113,000 acres in an area where three mountain ranges converge, while Nevada’s Gold Butte protects nearly 300,000 acres of desert landscapes that feature rock art, sandstone towers and wildlife habitat for bighorn sheep and the threatened Mojave Desert tortoise.

Two marine monuments in the Pacific Ocean also would be reduced under Zinke’s memo, which has not been officially released. The Associated Press obtained a copy of the memo.

President Donald Trump ordered the review earlier this year after complaining about a “massive land grab” by Obama and other former presidents.

“It’s gotten worse and worse and worse, and now we’re going to free it up, which is what should have happened in the first place. This should never have happened,” Trump said in ordering the review in April.