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?

Justin Trudeau said India made a "horrific mistake" by allegedly interfering in Canada's sovereignty as bilateral relations degraded to their lowest point in decades. The Canadian prime minister made the comment just two days after Ottawa expelled six Indian diplomats and New Delhi followed suit as the fallout from the investigation into the assassination of Sikh separatist leader Hardeep Singh Nijjar continued to damage ties between the two countries.