Colonel Trautman: I don't think you understand. I didn't come to rescue Rambo from you. I came to rescue you from Rambo. (00:45:25)
Rambo: NOTHING IS OVER! Nothing! You just don't turn it off! It wasn't my war! You asked me, I didn't ask you! And I did what I had to do to win, but somebody wouldn't let us win! And I come back to the world, and I see all those maggots at the airport, protestin' me, spittin', callin' me "Baby Killer!", and all kinds of vile crap! Who are they to protest me, huh?! Who are they, unless they been me and been there, and know what the hell they're yellin' about?!
Sheriff Teasle: Are you telling me that 200 men against your boy is a no-win situation for us?
Colonel Trautman: If you send that many, don't forget one thing.
Sheriff Teasle: What?
Colonel Trautman: A good supply of body bags. (00:48:05)
Sheriff Teasle: Whatever possessed God in heaven to make a man like Rambo?
Colonel Trautman: God didn't make Rambo. I made him.
Rambo: I could have killed 'em all, I could kill you. In town you're the law, out here it's me. Don't push it. Don't push it or I'll give you a war you won't believe. Let it go. Let it go.
John Rambo: Why are you pushing me? (00:06:40)
Rambo: For me, civilian life is nothing! In the field, we had a code of honor: You watch my back, I watch your's. Back here, there's nothin'!
Answer: At the start of the film when Rambo is causing all these problems, the Sheriff has no idea who John Rambo is (Vietnam War hero), so he thinks Rambo is just another America-disrespecting drifter (the American flag on Rambo's jacket). Also, Teasle is a law and order guy who does not want his town disturbed by outsiders. After the fireworks and Teasle finds out who Rambo is and also meets Colonel Troutman, Teasle's mission becomes personal: rage at the death of his best friend, humiliation in front of his deputies, the incompetence of the state National Guard to subdue Rambo, and also a generational factor: Teasle probably served in Korea or WW2, when America was top dog in the world, so he will not allow some hippie ex-soldier from a "lost" war best him.
Scott215
That's it. When they got the news that Rambo not only was a real war veteran, an ex-Green Beret, he was a war hero with a Medal of Honor; if Teasle's ego was Pearl Harbor, getting that info was December 7, 1941.