After threatening San Francisco with an invasion of National Guard troops to support their ICE storm troopers, Trump has backed off, supposedly after talking to some of his tech donors - I mean friends. Sources suggest, though, that he and Photo-Op Barbie took a look at pictures of the geography of San Francisco and realized that their goons wouldn’t make it up the first block (see reporting on ICE recruits . National Guard troops might not be much better. Then there’s the prospect of watching them trying to drive an SUV up and down hills in hot pursuit of the first Suspicious Brown-ish Person they see.
Terrain matters in conflict — quotes from Sun Tzu on emphasize this. And local people who know the terrain and navigate freely in it have a big advantage. (Some of us learned to parallel park on hills, dude.) Of course Trump could have been thinking of San Francisco as training ground for his invasion of … Bergen, Norway? Zurich, Switzerland? Lisbon, Portugal?
EDIT TO ADD: just in case you were in doubt, they DID cancel the invasion, but my speculation on why is kinda snarky. Though not by much!