The second amendment is why no one has thought about invading us. As the Japanese said, they could not occupy a territory where there was a guy with a rifle behind every tree.
Another interesting anecdote....
Shortly after the collapse of the Soviet Union in 1991, there was a military symposium in Europe attended by high ranking military officials from many countries, including America and the former Soviet Union.
During a break between meetings, the military officers gathered for an informal get together including drinks and snacks.
One of the American military officers asked his Russian counterpart if the Soviet Union ever considered invading the United States during the Cold War.
The Russian military officer laughed and said, “Oh no! You people have too many guns over there!”