JUNEAU, Alaska (AP) — President Donald Trump's eldest son agreed Tuesday with calls to block a proposed copper and gold mine near the headwaters of a major U.S. salmon fishery in southwest Alaska.

Donald Trump Jr. responded to a tweet by Nick Ayers, a former aide to Vice President Mike Pence and a senior adviser to the Trump campaign. Ayers, in his tweet, said he hoped the president would direct the U.S. Environmental Protection Agency to block the proposed Pebble Mine.

Trump Jr., in response, said: “As a sportsman who has spent plenty of time in the area I agree 100%. The headwaters of Bristol Bay and the surrounding fishery are too unique and fragile to take any chances with.”

This comes as the U.S. Army Corps of Engineers weighs a key permitting decision for the project, which is being pursued by the Pebble Limited Partnership. The Pebble partnership is owned by Canada-based Northern Dynasty Minerals Ltd.

An environmental review released by the corps last month stated that under normal operations, the alternatives it looked at “would not be expected to have a measurable effect on fish numbers and result in long-term changes to the health of the commercial fisheries in Bristol Bay.”

The review shows that Trump Jr. and Ayers are wrong, the Pebble partnership said in a statement, adding it is confident the corps will issue a final decision “in the next few months. We do not believe that the President will interfere with this statutory process.”

The EPA has said the Bristol Bay watershed supports the largest sockeye salmon fishery in the world and contains significant mineral resources. Under the Obama administration, the agency proposed restricting development in the region, though those restrictions were never finalized. The EPA retains the option to invoke that so-called veto process again if it elects to do so.

Pebble argued the proposed restrictions were unfair and said it should have a chance to have the project vetted through the permitting process.

Critics of the Pebble project have said the corps' review is deficient and complained of what they say has become a politicized process.

Alannah Hurley, executive director of United Tribes of Bristol Bay, which opposes Pebble, said she was shocked by Trump Jr.'s tweet.

“As shocking as it is, at the same time, to us, it's really a confirmation that Bristol Bay is valued by the nation, and people from every side of the political spectrum ... can agree on the fact that this place needs to be protected from Pebble Mine,” she said.