The Torah in Parashat Ki-Teseh (Debarim 23:7) commands with regard to the nations of Amon and Moab, “Lo Tidrosh Shelomam Ve’tobotam, Kol Yamecha Ad Olam” – that we may not “seek their peace and wellbeing.” This verse establishes a prohibition against offering these nations peace before going out to war against them. Normally, before Beneh Yisrael go out to war, they are required by Torah law to first offer a peaceful arrangement in order to avoid military conflict. When it comes to Amon and Moab, however, the Torah actually forbids offering peace before initiating conflict.
The Torah issues this command after introducing the prohibition against allowing men from these nations to join Beneh Yisrael in marriage. These nations, which descended from Lot, Abraham Abinu’s nephew, owed a debt of gratitude to Beneh Yisrael, and yet, they failed to offer assistance by bringing provisions when Beneh Yisrael traveled in the desert near their territory. On account of this lack of gratitude, which the Sefer Ha’hinuch describes as a form of “Achzariyut” (cruelty), the Torah bars the men of Amon and Moab from marrying into our nation, and forbids offering them peace before going to war against them.
This command is binding upon the men – because only men go out to war – and applies only when Beneh Yisrael reside in their land and fight wars. As a practical matter, this command became inapplicable once the Assyrian emperor Sanherib captured much of Eretz Yisrael and the surrounding regions, and exiled entire populations. After the Assyrian conquest, we can no longer identify the people of Amon and Moab, as the nations’ populations were all moved around throughout the region. Therefore, we cannot fulfill the special Misvot regarding these two nations.
The Rishonim address the question of why the Torah needed to issue this prohibition, given G-d’s command to Beneh Yisrael not to initiate hostilities against the nations of Amon and Moab (Debarim 2:9,19). If we are not permitted to wage war against these nations, then how can we commanded not to offer peace before waging battle?
The Rambam (Sefer Ha’misvot, Shoresh 3) explains that the command not to initiate hostilities against Amon and Moab applied only during the period of Beneh Yisrael’s travels through the wilderness. After Beneh Yisrael entered the Land of Israel, however, they were no longer forbidden from waging war against Amon or Moab.
The Ramban disagrees, and maintains that the command forbidding waging war against Amon and Moab applied even after Beneh Yisrael entered the land. According to the Ramban, the distinction lies between the original territory of Amon and Moab, and territories which they conquered and annexed. In these nations’ original territory, Beneh Yisrael are not permitted to wage war, as G-d gave these lands to the people of Amon and Moab. If, however, Amon and Moab expand their territory, then Beneh Yisrael are permitted to initiate hostilities in the annexed lands, and when they do, they are not permitted to first offer peace.