Air operations also are not seen as invasions, and the recent stealth strikes by the U.S. in Iran are not seen this way.
It appears to me that armed troops in place that are taking and holding territory for a prolonged duration are the definition.
The dictionary definition below is "the incursion of an army for conquest or plunder."
https://www.merriam-webster.com/dictionary/invasion
Is Maduro and his wife "plunder?" That would stretch this meaning, I think.