BILLINGS, Mont. (AP) — The Trump administration on Wednesday approved a right-of-way allowing the Keystone XL oil sands pipeline to be built across U.S. land, pushing the controversial $8 billion project closer to construction though court challenges still loom.

The approval signed by Interior Secretary David Bernhardt and obtained by The Associated Press covers 46 miles of the pipeline’s route across land in Montana that’s controlled by the Bureau of Land Management and the U.S. Army Corps of Engineers, said Casey Hammond, assistant secretary of the Interior Department.

Those segments of federal land are a small fraction of the pipeline’s 1,200-mile route, but the right-of-way was crucial for a project that’s obtained all the needed permits at the state and local levels.

The pipeline would transport up to 830,000 barrels (35 million gallons) of crude oil daily from western Canada to terminals on the U.S. Gulf Coast.

Project sponsor TC Energy said in a court filing that it wants to begin construction on the U.S.-Canada border crossing in Montana in April. Opponents promised to challenge those plans in court.

First proposed in 2008, the pipeline has become emblematic of the tensions between economic development and curbing the fossil fuel emissions that are causing climate change. The Obama administration rejected it, but President Donald Trump revived it and has been a strong supporter.

The stretch approved Wednesday includes all federal land crossed by the line, Hammond said. Much of the rest of the route is across private land, for which TC Energy has been acquiring permissions to build on.

Environmentalists and Native American tribes along the pipeline route say burning the tar sands oil will make climate change worse, and that the pipeline could break and spill oil into waterways like Montana’s Missouri River. They have filed numerous lawsuits.

Hammond said Interior officials and other agencies have done a thorough review of the potential effects on the environment. He said TC Energy had provided detailed plans to respond to any spill.

“We’re comfortable with the analysis that’s been done,” Hammond said.

Another oil pipeline in TC Energy’s Keystone network in October spilled an estimated 383,000 gallons of oil in eastern North Dakota. Critics say a damaging spill from Keystone XL is inevitable given the length of the line and the many rivers and other waterways it would cross beneath.