Zinke’s decision on the two protected sites comes after a review of public comments and personal conversations with area stakeholders, the Interior Department said. Unless Trump decides to go against Zinke’s recommendation, the announcement means the monuments will not be abolished, shrunk or otherwise weakened.

“When the President and I began the monument review process we absolutely realized that not all monuments are the same and that not all monuments would require modifications,” Zinke said in a statement.

Craters of the Moon is a monument in central Idaho more than 700,000 acres large, first established in 1924 and expanded by former President Bill Clinton in 2000. This “weird and scenic landscape” is home to expansive lava fields as well as cultural and natural resources.

“As a former geologist, I realize Craters of the Moon is a living timeline of the geologic history of our land on the Great Rift,” Zinke said in a statement Thursday. “Whether it’s hiking up the alien-like lava flows along the Spatter Cones, or just driving through the scenic loop, there’s a lot to see and learn at this historic location.”

Designated by Clinton in 2000, Hanford Reach National Monument, located in south-central Washington, spans some 200,000 acres that were once a security buffer around the Hanford Nuclear Reservation. Plutonium produced at the Hanford site was used in the atomic bomb dropped on Nagasaki, Japan, in 1945.

“Sportsmen and women from all over the country go to Hanford Reach for some of the best fishing and bird hunting around,” Zinke said. “It’s also home to some of the most well-preserved remnants of human history in the area.”

Twenty-seven national monuments — most famously, the 1.35-million-acre Bears Ears National Monument in Southern Utah — were targeted by Trump’s executive orders, which tasked the departments of Interior and Commerce with reviewing land and marine national monuments designated or expanded under the Antiquities Act. Monday marked the end of a 60-day public comment period Interior held for its review. More than 1.4 million comments were submitted, according to .

Sen. Maria Cantwell (D-Wash.) said she reminded Zinke on Wednesday that his boss does not have the authority to rescind monument designations and that taxpayer money should never have gone toward such a review.

“Now that Secretary Zinke agrees that the protection for the Hanford Reach National Monument should not be changed, the Trump Administration should abandon this review and the ill-advised effort to undermine national monuments altogether,” she said in a statement. “An attack on one of our national monuments is an attack on all of them.”

At a press conference outside the U.S. Capitol on Tuesday, Cantwell said Theodore Roosevelt, who signed the Antiquities Act into law in 1906, is likely “rolling over in his grave.”

While four legal scholars concluded in May that Congress, not the president, has the sole legal power to rescind or modify national monuments, Trump appears set on trying to weaken monument status. He has claimed recent presidents have abused the 1906 law “to lock up millions of acres of land and water, and it’s time we ended this abusive practice.”

Last month, Zinke submitted an interim report recommending Trump shrink Bears Ears’ boundaries. Instead of the large area designated by former President Barack Obama, “it would have been more appropriate to identify and separate the areas that have significant objects to be protected,” Zinke wrote.

He is expected to issue a final report on his larger monuments review in late August.

Sixteen presidents have used the Antiquities Act to designate 157 monuments; however, no president has ever tried to revoke a designation.