Didn't the king know whom Haman's decree was against?

The chapter doesn't say what the king knew. It gives his question: "Who is he, and where is he who dared presume in his heart to do so?" (7:5). When Haman had spoken to the king, he named no people: "There is a certain people scattered abroad and dispersed among the peoples in all the provinces of your kingdom" (Esther 3:8). The king gave Haman his ring (Esther 3:10) and said, "The silver is given to you, the people also, to do with them as it seems good to you" (Esther 3:11). The letters, "to destroy, to kill, and to cause to perish, all Jews" (Esther 3:13), were written in the king's name: "It was written in the name of King Ahasuerus, and it was sealed with the king’s ring" (Esther 3:12). And "Esther had not made known her people nor her relatives" (Esther 2:10). The book gives these verses and doesn't say what the king understood, or when, and these notes don't guess.