Canada (or US) is no saint here. I think India is just learning these tactics from West. If you can't get the criminals and terrorist in front of your court because they operate from other countries which encourages such people and use them as a tool to interfere and destabilize your society, you are left with no option but to get rid of them using similar tactics.
Do you actually believe that Canada, the US, or any other part of the West is trying to "interfere and destabilize" India? If so you really need to touch grass and put down the propaganda pipe. Many Indians seem to think that because Canada doesn't actively stomp on activities that you personally don't approve of it's sanctioning them, seemingly having no concept of how freedoms work.
If the West were trying to destabilize India I suspect it would be incredibly easy to achieve, which is exactly why there is that defensiveness and hitting at shadows. But the West isn't because India has long been a useful counter to regional powers.
What is absolutely true is that the Modi government is spectacularly corrupt. Every opponent of Modi is a "terrorist" -- even opponents in government. The government is falling further and further down the well towards fascism, all while proud Indians convince themselves that everyone else is actually the problem.
For someone so uninformed about the geopolitical history of India, you speak far too confidently.
This is a common tendency for many Americans, read 10 uni-dimensional articles in your favorite newspaper on some topic, do not bother to read any history on said topic, then come to strong opinions and bully people who see things differently. Maybe it is you who should put down the "propaganda pipe" and consider this issue for the complicated nuanced thing it is.
If they had solid evidence the person committed a serious crime, particularly actual terrorism, it'd have been no problem getting Canada to turn them over.
The real issue is they wanted to kill someone who wasn't a criminal. Which, ultimately, is just plain old homicide.
I just checked and India and Canada do have an extradition treat (unlike Canada and China), so there is merit to this comment. They had requested extradition of Nijjar, but didn’t give time for the request to even go to court.
The USA has employed drone strikes on non-US soil against Al Qaeda members who were, as I recall, quite eager to terrorize and destabilize "the great Satan", as they called it.
