What does it mean that Sichon didn’t trust Yisrael?

In last week’s Haftara, we find a discussion between Yiftach and the king of Amon.  The king tells Yiftach that he is determined to take back the land that the Jewish people took from him when they left Mitzrayim.  Yiftach responds that it wasn’t the Jews’ fault that Amon lost its land – Yisrael had asked to pass through the land of several nations peacefully, but instead Sichon the King of the Emori waged war on the nation of Israel.  God granted Yisrael victory, and it was because of their victory in that unwanted war that Yisrael conquered the lands of Amon.