Khalistani separatism on Canadian soil has long been Trudeau’s blind spot. More than a year after he first alleged Indian government links to the Nijjar murder, what explains this week's escalation?

Experts say neither country is expected to back down after strong language used in recent exchanges, tit-for-tat expulsions of diplomats.

Canada's Prime Minister Justin Trudeau accused India Monday of making a "fundamental error," as an escalating row over the killing of a Sikh separatist on Canadian soil last year saw both countries expel each other's ambassadors.