A disagreement has surfaced in a moment of relative calm in cross-border affairs, with a trade disagreement now resolved and pandemic travel rules eased.
This new dispute has been quietly simmering for months and boiled over on a public stage Thursday.
It involves dysfunction in a Canada-U.S. program for pre-screened trusted travellers, who can cross the border more quickly with what's known as a NEXUS card.
The U.S. has shuttered offices in Canada that process applications for these cards while it presses for changes to the program.
A Canadian official made clear her country's displeasure in an unusually curt assessment before a high-level audience in Washington.
"I'm going to be super undiplomatic and blunt here because I think this is important for friends sometimes," said Kirsten Hillman, Canada's ambassador to the U.S.
"The [NEXUS] program is being held hostage.… It's disappointing and it's frustrating for us."
The closure of facilities stems from a disagreement about immunity from prosecution — not unlike the protections for diplomats.
The U.S. government contends that its employees in NEXUS offices deserve similar immunity from Canadian prosecution while doing their job in Canada.
These protections already exist for U.S. border agents at Canadian airports working in customs pre-clearance sites; in the U.S. view, some of these NEXUS offices are co-located in the same facility and it makes no sense for different rules to apply in different parts of the office.
There's now a backlog of more than 334,000 people awaiting NEXUS cards and Hillman said it's getting worse every day.
She disputed news reports that indicated that the core irritant involves whether U.S. officials can carry guns on Canadian soil.
Hillman told CBC News that's not the issue: "They're not asking for the right to carry firearms. They're not." She said the issue is Americans wanting immunity from prosecution for acts committed by Americans while working in a Canadian-based office.
She said it's complicated and these offices are not like airport pre-clearance facilities, because some are located within Canadian cities.
She said she's discussed the issue with the head of the Department of Homeland Security, Alejandro Mayorkas, and he's committed to the NEXUS program.
This was excerpted from the 13 October 2022 edition of CBC News.