In Naruto's view, the essence of this wager was to influence Gaara's mindset by demonstrating things to him.
Due to its desert environment, Sunagakure was relatively isolated, and regularly sending letters and photographs to Gaara would give him a new channel to understand the world and experience love and bonds.
Therefore, things like "you cannot attack Konoha" were all mere excuses, and Naruto was crystal clear about that in his heart.
Chapter 92