Bribing the Enemy for Peace?

“Then Menahem smote [attacked] Tiphsah, and all that were therein, and the coasts thereof from Tirzah: because they opened not to him…and all the women therein that were with child he ripped up. In the nine and thirtieth year of Azariah king of Judah began Menahem the son of Gadi to reign over Israel, and…