What does Judges 11:12 mean?

Jephthah has just been made ruler of Gilead and leader of its fighting forces (Judges 11:11). He immediately takes ownership of his new role and goes to work. Jephthah acts very much as a king might do in similar circumstances. He presents himself as the rightful representative of Gilead; as such, attacks from the Ammonites are a personal insult against himself. He sends messengers to the king of the Ammonites to begin diplomatic negotiations. Jephthah's aim is to understand why the Ammonites believe Gilead belongs to them, rather than to Jephthah and his people.

His first message implies a question: What do you have against me that you feel justified in fighting against my land? What right do you think you have to our territory?