What does 1 Chronicles 19:12 mean?

Joab told Abishai, 'If the Arameans are too strong for me, come help me. If the Ammonites are too strong for you, I'll come help you. We'll support each other.' 1 Chronicles 19:12 - Modern Text Bible

(Joab and Abishai make a plan to back each other up, depending on which side needs help. It's a practical, brotherly strategy.)