“The Swiss Method”
I always thought of this to be a very crazy human thing to do:
One of the interesting and counter-intuitive military defense tactics is from the Swiss. Bridges and tunnels are important to moving, especially in mountainous terrain. So most try to keep them functional to move supplies. As a last resort, many Bridges and tunnels are rigged to explode in the event of an invasion to prevent the enemy from advancing.
I always imagined this would be something only humans would do and would be totally foreign to aliens.
“General Foaxi, we have taken control of orbit of the human colony.”
“Excellent, prepare the ground invasion forces. We must land at their spaceport to be successful.”
Later…
“General, we have a report in from the ground. The invasion forces have been defeated.”
“How? We had superior numbers and firepower.”
“Apparently the spaceport was rigged to explode, a miniature nuclear device was buried beneath the surface. When human forces retreated, they detonated the bomb.”
“Well those humans are fools! Now they can never launch a counter attack!”
“Unfortunately we cannot launch a second invasion sir. All our plans relied on the spaceport staying intact. Most of the planet is uncharted and what is known is mostly mountainous and unpassable. We can only hope the humans are dumb enough to build a new spaceport. Which I doubt.”