JUNEAU — President Donald Trump said Wednesday he would “listen to both sides” after his eldest son and a campaign adviser urged him to intervene to block a proposed copper and gold mine in Alaska’s Bristol Bay region.

Donald Trump Jr. on Tuesday agreed with a tweet from Nick Ayers, a former aide to Vice President Mike Pence and a senior adviser to the Trump campaign, expressing hope the president would direct the U.S. Environmental Protection Agency to block the proposed Pebble Mine.

Trump Jr., in response, wrote: “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.”

The EPA has said the Bristol Bay watershed supports the largest sockeye salmon fishery in the world and contains significant mineral resources. An environmental review released by the U.S. Army Corps of Engineers last month — and assailed by critics as deficient — 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 corps has yet to make a permitting decision. When it does, it could issue a permit, approve a permit with conditions or issue a denial. The project, should it advance, also would face a state permitting process.

On Wednesday, the president told reporters his son “has some very strong opinions and he is very much of an environmentalist.”

Trump said there was an upcoming briefing, but it wasn’t clear who would be involved or what it would entail. The White House said it was not in a position at this time to comment further.

“I’ve done a lot for Alaska. I love Alaska. It’s a special place,” Trump said.

Tom Collier, CEO of the Pebble Limited Partnership, which is seeking to build the mine, has hailed the corps’ review as thorough and a positive for the project. The Pebble partnership is owned by Canada-based Northern Dynasty Minerals Ltd.

Mike Heatwole, a Pebble spokesperson, said the Trump administration “has already spoken” about the project through that review process.

“Recall that this administration is the one that brought the Pebble issue away from the political route pursued by the preemptive veto of the Obama-era EPA and back to the traditional regulatory review process,” he said by email.

The EPA under the Obama administration proposed restricting development in the Bristol Bay region but never finalized the restrictions. The agency retains the option to invoke that so-called veto process again if it decides to do so.

The EPA responded to questions Wednesday with a statement answering none of them.

Daniel Cheyette, a vice president for lands and natural resources for Bristol Bay Native Corp., which opposes the mine, said he thinks people are weighing in now because the project faces a key decision point.

“We encourage President Trump and his administration to listen to the science and the diverse voices who oppose Pebble mine and deny the project a Clean Water Act permit,” he said in a statement.