The Midrash Shmuel says in the name of the Ritvo that it refers to above, to the shalom of the behavior of Hashem. I think it means that the kitrugim should get convinced and agree with the defenders. That can be the meaning עושה שלום במרומיו He, Hashem, the same way makes peace in the heavens, הוא יעשה שלום עלינו should make peace on us, caring for and loving each other and then ואמרו אמן the Malochim will say Amen.
