Canada accused India of killing a citizen on its soil, New Delhi dismissed the allegations as «absurd».
Relations plunged and diplomats were expelled.
This week, after an Indian national was charged with plotting to assassinate a Khalistani separatist leader Gurpatwant Singh Pannun in the United States, commentators noted New Delhi's response to its superpower ally and largest trading partner was «starkly different».
Indian foreign ministry spokesman Arindam Bagchi said it was a «matter of concern» and a special committee had been set up — a «pointer to how seriously» it is being taken, the Hindustan Times wrote in an editorial this week.
But, despite New Delhi's «starkly different» and «much more cooperative» reaction, journalist Shubhajit Roy feared it would «cast a shadow» on the key relations.
«The depth of its strategic ties with the US give it some manoeuvring room, but New Delhi has its task cut out,» Roy wrote in the Indian Express.
'Unsettling realisation'
For Prime Minister Narendra Modi — who revelled in centre-stage attention hosting G20 leaders in September — the assassination allegations threaten to puncture well-crafted efforts to burnish his image abroad.
«It will create a greater wariness in dealing with Modi,» said Hartosh Singh Bal, executive editor at The Caravan magazine, suggesting the charges would result in a reduction of intelligence sharing with New Delhi.
«What India stands accused of is rogue behaviour and it will leave allies unwilling to trust a leadership that is willing to act so,» he told AFP.
While Washington has embraced India as an ally in the face of a rising China, accusations of murder plots threaten to throw the relationship off balance.
«US officials must now grapple