Canada postponed its much-ballyhooed trade mission to India without explanation, but the prime ministers of the two countries clashed at the recent G20 Summit about Sikh separatist protests.

On the Canadian federal government trade website, International Trade Minister Mary Ng had hyped the trip, scheduled for Oct. 9, as important in its strategy to expand trade in the Indo-Pacific region. At the top of the website is a terse message: “This event is postponed,” it said Friday, with no explanation.

Relations between the two countries have been strained for some time, as illustrated by the exchange between Canadian Prime Minister Justin Trudeau and his Indian counterpart, Narendra Modi, at the G20 Summit last weekend in New Delhi.

Before leaving for the summit, Trudeau said he would broach concerns about India interfering in Canada. India has been critical of protests by Canadian Sikhs in Canada who want to take control of the Punjab territory in India to form their own state.

Modi took Trudeau aside at the summit and chided him about the Sikh separatist protests, while Trudeau said freedom of speech in Canada guaranteed peaceful demonstrations.

But the dispute has been simmering for some time. India’s envoy to Canada said two weeks ago that Ottawa had postponed trade talks, although Canada’s announcement did not happen until Friday.

India has long argued that the Sikhs in Canada, who have argued for the Punjab state to become independent, have undermined New Delhi’s national security.