US President Donald Trump could never be accused of backing away from a political fight, whether it's trade, gun control or immigration.

But there's one big fight involving Mr Trump you probably haven't heard much about and it could determine the future of public lands, ancient Native American art, states' rights and conservation in the US.

Mike Noel, Republican State House representative in Utah, supports Donald Trump's decision. ( ABC News: John Mees )

On one side is Mr Trump, his family and Utah's conservative Mormon majority. On the other an unprecedented coalition of Native American tribes, environmental groups and some big-money backers.

It's all over national monuments — similar to Australia's national parks — which the President is gutting with an intent and on a scale not seen by any of his predecessors.

Imagine Prime Minister Malcolm Turnbull reducing the size of Uluru by 85 per cent — that's exactly what Mr Trump did to Bear's Ears National Monument, making the announcement to beaming Republicans in Utah's capital, Salt Lake City.

Republican State House Representative, Mike Noel, was there when Mr Trump signed the order.

"When you turn the management of the forest over to the tree huggers, the bird and bunny lovers and the rock lickers, you turn over your heritage, you turn over your rights that you had as a citizen to take care of this country," he told 7.30.

'This is part of my culture too'

Vaughn Hadendeldt showing ancient rock art to Conor Duffy at Bear's Ears national monument, Utah ( ABC News )

It's a six-hour drive south from Salt Lake to Bear's Ears, and after hiking down into canyons with archaeologist and guide Vaughn Hadenfeldt the ABC is shown, literally, a very different picture.

Ancient Native American rock art, some of it considered among the oldest in America, depicts the lives of the first humans to live here roughly 13,000 years ago.

"As an American I'm kind of a Native American, too," Mr Hadenfeldt said.

"I was born in this country, I think this is a part of my culture too, my history."

"This is the land, it was here when I was born. I connect to this too."

The rock art panel is still protected but Mr Hadenfeldt said even more spectacular and rarer art would no longer have protection under the changes and could even be subject to mining, as well as drilling for oil and gas.

And it's not just art that's at risk.

We visited two-storey ruins made using an early clay-baking technique by the Puebloan tribe 800 years ago.

They turned it into a hill fort to protect themselves against attacks from rivals.

"This has a real significance for Native Americans and we should respect that," Mr Hadenfeldt said.

"I think it's time in our history we step up a bit and take their concerns a lot more seriously.

"We have people in this area who dismiss that whole Native American viewpoint."

Looting, vandalism, grave robbing 'erasing' Navajo history

Nellie Begay and Tammy Nakai weave baskets ( ABC News: John Mees )

They certainly feel ignored at our next stop, the local Navajo reservation where mother and daughter Nellie Begay and Tammy Nakai weave baskets in a small hut warmed by a fire.

Tammy Nakai says her people have been harvesting food and materials in Bears Ears for hundreds of years and they need it to keep a connection with their ancestors, history and culture.

She fears the new rules mean they'll be shut out of ancestral lands.

"Different trees, different barks, different herbs that we need because, if it weren't for that, we wouldn't have anything today," she said.

"That's one thing that keeps our culture alive."

A 500-year-old Hogan (tradition Navajo dwelling) in Utah ( ABC News )

Cynthia Wilson, a traditional Navajo foods expert, and Jonah Yellowman, a Navajo spiritual guide, take us on a drive up a steep mountain and, in light snow, show us a 500-year-old Hogan, the traditional dwelling of the Navajo people.

The timber remains are all that's left. It once would have had pottery and bark to keep the elements out.

"When I see the threat to this area such as looting, vandalism and grave robbing, I see that as erasing our history as Native Americans," Ms Wilson said.

"Knowing that this area has been left out of the current monument — it just shows how much Native Americans are still ignored to this day."

Donald Trump Jr influential in law change

The chair in which Donald Trump signed the reduction in the Bear's Ears National Monument ( ABC News: John Mees )

Back in Salt Lake City, the conservative Mormon majority don't see it that way, and have memorialised the chair Mr Trump sat on when he signed the order.

Mike Noel said it was a gutsy action most presidents wouldn't take, and support from Mr Trump's family was crucial to making it happen.

"Part of the help that happened here was that his oldest son, Donald Jr, has a really great passion for hunting, so he's out a lot," he said.

"He's a tremendous individual, great hunter, great outdoorsman, he's not a pansy. I mean he literally gets out there and hikes."

They believe they've done a great job protecting the land and should have the right to continue to do so.

Under the old terms of the national monument, grazing and hunting were allowed, but Mr Trump's action means mining and resource industries can now survey the area too.

It was initially denied that resources were a factor, but it later emerged a uranium firm, Energy Fuels, lobbied for the monument to be shrunk.

Its chief executive, Mark Chalmers, who worked for Australian politician Ian Macfarlane, is furious his company is getting the blame, saying it only asked for a 2.5 per cent cut.

"We have no intention in developing anything in Bears Ears. We've said that multiple times and a number of other parties refuse to hear that," he said.

"So this is a non-issue, non-story from our perspective, but certain people keep trying to rev it up.

"And usually the title in the US that has become quite common is 'fake news'. Well, this is fake news!"

Mr Chalmers said his company employed many Navajo people.

"I think the important thing is when people try to ping our company against the indigenous people — it is just flat wrong." he said.

National monument changes uniting Native American tribes

Navajo spiritual guide Jonah Yellowman and Navajo foods expert Cynthia Wilson are concerned their culture will be destroyed. ( ABC News: John Mees )

Nevertheless the reduction has united Utah's five Native American tribes.

With their history of warring, it's the first time they've come together because they say their culture is at risk.

"It's disappointing. We got this as a monument and here, you know, people will just come in here and destroy these things. And some of the things, our history is here," Mr Yellowman said.

And the tribes have high-powered support, with outdoor clothing giant Patagonia running a national campaign to have Mr Trump's decision reversed.

In Salt Lake City though they are accusing Patagonia's billionaire founder of hypocrisy, saying hikers do their own damage.

"He's making money off of public lands — he's bringing people in," Mr Noel said.

"They're creating problems out there."

"They're walking on the land and a lot of them are defecating on the land."

Compromise seems unlikely.

Mormons are deeply distrustful of the Federal Government and many Native American tribes are deeply distrustful of the state's Mormon politicians.

What seems certain is that the case is likely headed to the Supreme Court, and the ruling will determine if future monuments can be scratched at the stroke of a pen.

You might not have heard much about Bears Ears yet but you certainly will once it lands in court.