Dictionary definition of "invasion" and "invasive" with regards to military incursions tend to emphasize the size of the force. Same for "invasive species" and invasion biology.

But you can also have an invasion of privacy or invasive surgery. In that sense it is about unwelcome intrusion into one's body / sovereignty.

And people are entertained by news articles with titles like, "10 times countries accidentally invaded their neighbors." Clearly the intent to violate sovereignty matters.

I think you can argue that the Bin Laden raid was and invasion into Pakistan. Anytime a military forces enters uninvited, that's an invasion.