BILLINGS, Mont. (AP) — A Canadian company has built the first piece of the disputed Keystone XL oil sands pipeline across the U.S. border and started work on labor camps in Montana and South Dakota. However, Calgary-based TC Energy has not resolved a recent courtroom setback that cancelled a key permit and would make it much harder to complete the $8 billion project. The 1,200-mile (1,900-kilometer) pipeline from Alberta to Nebraska was stalled for much of the past decade before President Donald Trump was elected and began trying to push it through to completion. Environmentalists and Native American tribes are bitterly opposed to it because of worries over oil spills and that burning the fuel would make climate change worse.