The U.S. Army Corps of Engineers issued a letter to Pebble Limited Partnership requiring the company behind the proposed Pebble Mine in Alaska to detail the extra steps it will take to mitigate “unavoidable adverse impacts to aquatic resources.”

The letter gives Pebble Limited Partnership 90 days to provide the report and delays the final decision on the mine. The letter was published online two days after Politco reported that the Trump administration had planned to block the project following political pressure from conservatives, including Donald Trump Jr. and Fox News host Tucker Carlson, who have rallied against the mine.

The U.S. Army Corps of Engineers (USACE) had previously issued an environmental impact statement that found that the proposed project would not impact salmon harvests in the Bristol Bay area. That decision reversed an Obama-era determination that it would. The most recent assessment also said the project would impact wetlands and streams.

The Hill reported that the Army Corps said it will “review the compensatory mitigation plan upon submittal to determine if the amount and type of compensatory mitigation offered is sufficient to offset the identified unavoidable adverse impacts to aquatic resources and overcome significant degradation at the mine site.”

The letter said that discharges from the mine site would directly or indirectly affect 1,143 ha (2,825 acres) of wetlands, 53.6 ha (132.5 acres) of open waters and 208 km (129.5 miles) of streams and that discharges from its transportation corridor would impact 186 ha (460 acres) of wetlands, 93.7 ha (231.7) acres of open waters and 89 km (55.5 miles) of streams.

Pebble Limited Partnership CEO Tom Collier downplayed the significance of the new requirements from the Army Corps of Engineers.

“Based on our understanding of the substance of the letter, our discussions with the state, our substantial work in the field and our discussions with the USACE we believe our final Comprehensive Management Plan submission will be submitted within weeks and will satisfy all of the requirements of the letter,” Collier said in a statement.

“Anyone suggesting a different opinion—i.e. that Pebble will not be able to comply with the letter or that such compliance will significantly delay issuing a [decision]—must be ignorant of the extensive preparation we have undertaken in order to meet the requirements of the letter,” he added, saying the company “will share more details of our initial plan as they become more defined.”

Collier denied that the recent attention from prominent conservatives played a role in the USACE’s letter.

"A clear reading of the letter shows it is entirely unrelated to recent tweets about Pebble and one-sided news shows. The White House had nothing to do with the letter ... This is the next step in what has been a comprehensive, exhaustive two-and-a-half-year review of the project. Nothing in the letter is a surprise to us or them,” he said.

The Environmental Protection Agency proposed under the Obama administration to preemptively veto a permit for the mine. The Trump administration reversed that action last year.