Meaning of 裏切 in Japanese

I had imagined that the newbies fresh from university would probably be stuck with all the backstage work - collecting reference material, getting copies and such but I couldn't have been proved more wrong.

The traitor betrayed his country to the enemy.

Tracing a renegade's family background, you'll find him the black sheep.

Never betray the trust of your friends.

Don't go back on your promise.

A true friend would not betray you.

A true gentleman would not betray his friends.

She's determined to get back at her friend for stabbing her in the back.

She boiled over with rage at his betrayal.

She betrayed his trust.