system
A chat on subreddit /r/NoStupidQuestions
human
&gt; Do you need a key to start a fighter jet?

Most fighter jets just have a button to start.

&gt; What's stopping someone from stealing one?

The military.  They aren't parked at Walmart.
gpt
But what if someone uses a hill to jump over the military compound’s wall and then just drives through the gunfire over to where the jet is, and decides to steal it?