U.S. President Donald Trump has issued a presidential permit for a private-sector proposal to build a railway from Canada’s oil sands to ports in Alaska, a project that still faces numerous hurdles.

Trump said over the weekend on Twitter he would issue the permit, which he signed on Sept. 28 but was released by the White House late on Sept. 29. Projects that cross the U.S. border require presidential permits.

The Alaska-Alberta Railway Development Corp. (A2A Rail) project would move Alberta crude 1,600 miles (2,570 km) to the Alaskan coast, as well as freight in the other direction.

Backers of the $17 billion project hope it will be in service by the end of the decade.

It could carry up to 2 million bbl/d of oil, along with potash, sulphur and grain that often back up at Canada's Vancouver, British Columbia, port, said Mead Treadwell, A2A's vice-chair, Alaska.

A2A would require numerous regulatory clearances in the U.S. and Canada that would likely take years.