BILLINGS, Mont. (AP) — Attorneys for President Donald Trump’s administration assert that he holds the power to dismantle national monuments designed to preserve historical and archaeological sites across expansive areas, including two in California established by his predecessor at the behest of Native American tribes.

A legal opinion from the Justice Department, released Tuesday, rejected a 1938 determination that prior presidents’ monuments under the Antiquities Act are irrevocable. The department stated that presidents can rescind monument designations if protections are deemed unnecessary.

This conclusion emerges as the Interior Department under Trump evaluates adjustments to monuments nationwide as part of the administration’s drive to enhance U.S. energy production.

Sen. Martin Heinrich of New Mexico, the ranking Democrat on the Senate Natural Resources Committee, said that at Trump’s order, “his Justice Department is attempting to clear a path to erase national monuments.”

Trump in his first term reduced the size of Bears Ears and Grand Staircase Escalante National Monuments in Utah, calling them a “massive land grab.” He also lifted fishing restrictions within a sprawling marine monument off the New England Coast.

Former President Joe Biden reversed the moves and restored the monuments.

The two monuments singled out in the newly released Justice Department opinion were designated by Biden in his final days in office: Chuckwalla National Monument, in Southern California near Joshua Tree National Park, and Sáttítla Highlands National Monument, in Northern California.

The Democrat’s declarations for the monuments barred oil and natural gas drilling and mining on the 624,000-acre (2,400-square-kilometer) Chuckwalla site, and the roughly 225,000 acres (800 square kilometers) Sáttítla Highlands site near the California-Oregon border.

Chuckwalla has natural wonders including the Painted Canyon of Mecca Hills and Alligator Rock, and is home to rare species of plants and animals like the desert bighorn sheep and the Chuckwalla lizard. The Sáttítla Highlands include the ancestral homelands of the Pit River Tribe and Modoc Peoples.

All but three presidents have used the 1906 Antiquities Act to protect unique landscapes and cultural resources. About half the national parks in the U.S. were first designated as monuments.

But critics of monument designations under Biden and Obama say the protective boundaries were stretched too far, hindering mining for critical minerals.

Deputy Assistant Attorney General Lanora Pettit wrote in the Trump administration opinion that Biden’s protections of Chuckwalla and the Sattítla Highlands were part of the Democrat’s attempts to create for himself an environmental legacy that includes more places to hike, bike, camp or hunt.

“Such activities are entirely expected in a park, but they are wholly unrelated to (if not outright incompatible with) the protection of scientific or historical monuments,” Pettit wrote.

Trump in April lifted commercial fishing prohibitions within an expansive marine monument in the Pacific Ocean created under former President Barack Obama.

Environmental groups said Tuesday’s Justice Department opinion doesn’t give him the authority to shrink monuments at will.

“Americans overwhelmingly support our public lands and oppose seeing them dismantled or destroyed,” said Axie Navas with The Wilderness Society.

Biden established 10 new monuments, among them the site of a 1908 race riot in Springfield, Illinois, and another on a sacred Native American site near the Grand Canyon.

Since 1912, presidents have issued more than a dozen proclamations that diminished monuments, according to a National Park Service database.

Dwight Eisenhower was most active in undoing the proclamations of his predecessors as he diminished six monuments, including Arches in Utah, Great Sand Dunes in Colorado and Glacier Bay in Alaska, which have all since become national parks.

Trump’s moves to shrink the Utah monuments in his first term were challenged by environmental groups that said protections for the sites safeguard water supplies and wildlife while preserving cultural sites.

The reductions were reversed by Biden before the case was resolved, and it remains pending.

President Theodore Roosevelt signed the Antiquities Act after lobbying by educators and scientists who wanted to protect sites from artifact looting and haphazard collecting by individuals. It was the first law in the U.S. to establish legal protections for cultural and natural resources of historic or scientific interest on federal lands.