Ties between Canada and India have sunk to a low. This week, Canadian Prime Minister Justin Trudeau alleged India was potentially involved in the killing of a Sikh separatist in a suburb of Vancouver, a charge India denies. WSJ’s Tripti Lahiri explains why the crisis is now ensnaring other big democracies. Further Reading: - India Suspends Visas for Canadians as Rift Over Killing Deepens  - India Blasts Canada Over Trudeau’s Allegation That It Played Role in Killing  Learn more about your ad choices. Visit megaphone.fm/adchoices