The United States has paused negotiations with Canada on a key water-sharing treaty as Donald Trump continues both his threats to annex his northern neighbour and to upend major agreements governing relations between the two counties.

The sprawling Columbia River, which originates in south-eastern British Columbia and terminates in the Pacific Ocean on the Oregon-Washington border, is one of the largest watersheds on the continent. The immense volume of water that moves along its 1,200-mile (1,900km) route produces roughly 40% of US hydroelectric power and nearly half the hydropower in BC.

The treaty first came into effect in 1964, after devastating floods nearly two decades before that destroyed Oregon’s second-largest city and swaths of southern British Columbia.

Under former president Joe Biden, the two countries reached an in-principle deal on a new version of the decades-old treaty in July, ahead of the September expiration deadline of the treaty.

Despite a concerted push on both sides to finalize a deal before Trump took office, however, the final details of the treaty remain unfinished, with only a three-year interim agreement in place.