President Donald Trump on Monday took the rare step of scaling back two sprawling national monuments in Utah, declaring that “public lands will once again be for public use” in a move cheered by Republican leaders who lobbied him to undo protections they considered overly broad.

The decision marks the first time in a half century that a president has undone these types of land protections. Tribal and environmental groups oppose the decision and are expected to go to court in a bid to stop Trump and Interior Secretary Ryan Zinke.

A long wall of stone formations are shown here in the Bears Ears National Monumen on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]
A long wall of stone formations are shown here in the Bears Ears National Monumen on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]

Trump made the plan official during a speech at the State Capitol, where he signed proclamations to shrink the Bears Ears and Grand Staircase-Escalante national monuments. Both monuments encompass 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).

This time exposed shot taken at midnight, shows the stars and the two bluffs known as the
This time exposed shot taken at midnight, shows the stars and the two bluffs known as the "Bears Ears" in the Bears Ears National Monument on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]

Grand Staircase-Escalante National Monument, 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).

A farm sits at the foot of sandstone formations in the Grand Staircase-Escalante National Monument on May 11, 2017 outside Escalante, Utah. [George Frey | Getty Images]
A farm sits at the foot of sandstone formations in the Grand Staircase-Escalante National Monument on May 11, 2017 outside Escalante, Utah. [George Frey | Getty Images]
The
The "Moonhouse" in McLoyd Canyon is part of Bears Ears National Monument, near Blanding, Utah. [Rick Bowmer | Associated Press (2016)]
Ancient granaries, part of the House on Fire ruins are shown here in the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017, outside Blanding, Utah. [George Frey | Getty Images]
Ancient granaries, part of the House on Fire ruins are shown here in the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017, outside Blanding, Utah. [George Frey | Getty Images]
Two people hike up the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]
Two people hike up the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]
Sandstone formations are shown here in the Hells Backbone and Calf Creek area of the Grand Staircase-Escalante National Monument on May 11, 2017, outside Boulder, Utah. [George Frey | Getty Images]
Sandstone formations are shown here in the Hells Backbone and Calf Creek area of the Grand Staircase-Escalante National Monument on May 11, 2017, outside Boulder, Utah. [George Frey | Getty Images]
The Upper Gulch section of the Escalante Canyons within Utah's Grand Staircase-Escalante National Monument features sheer sandstone walls, broken occasionally by tributary canyons. Utah has long stood out for going far beyond other Western states in trying to get back control of its federally protected lands. [Douglas C. Pizac | Associated Press]
The Upper Gulch section of the Escalante Canyons within Utah's Grand Staircase-Escalante National Monument features sheer sandstone walls, broken occasionally by tributary canyons. Utah has long stood out for going far beyond other Western states in trying to get back control of its federally protected lands. [Douglas C. Pizac | Associated Press]
Four ancient hand prints are seen here on a sandstone wall at the House on Fire ruins in the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]
Four ancient hand prints are seen here on a sandstone wall at the House on Fire ruins in the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]
Sandstone formations are shown here on the western edge of the Bears Ears National Monument on May 11, 2017 outside Blanding, Utah. [George Frey |Getty Images]
Sandstone formations are shown here on the western edge of the Bears Ears National Monument on May 11, 2017 outside Blanding, Utah. [George Frey |Getty Images]
This is a look inside an ancient granary, part of the House on Fire ruins in the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]
This is a look inside an ancient granary, part of the House on Fire ruins in the South Fork of Mule Canyon in the Bears Ears National Monument on May 12, 2017 outside Blanding, Utah. [George Frey | Getty Images]
Sandstone formations are shown here in the Grand Staircase-Escalante National Monument on May 10, 2017 outside Boulder, Utah. [George Frey | Getty Images]
Sandstone formations are shown here in the Grand Staircase-Escalante National Monument on May 10, 2017 outside Boulder, Utah. [George Frey | Getty Images]