The physical landscape of a city often reflects a deeper spiritual reality. Jerusalem is not built upon the highest peak in its region. Instead, it rests among a ring of surrounding mountains of similar height, which act as a natural wall and fortification [ביאור שטיינזלץ]. The primary approach among commentators is that this geography serves as a direct comparison for divine protection. Just as these physical mountains encircle the city, God surrounds and guards the people who place their trust in Him. Because of His presence residing within the city, hostile forces are kept at bay and prevented from laying siege to it [אבן עזרא, מצודת דוד].
However, natural defenses alone do not guarantee absolute safety. Physical mountains can be overcome, and nations can still conquer a fortified city. Therefore, true and unshakable security comes not from the landscape, but from the fact that God Himself surrounds His people. His divine protection is vastly stronger than any physical barrier [רד״ק, מלבי״ם].
Furthermore, this divine presence is permanent and does not depend on the current state of the nation. The mountains stand firmly in place around Jerusalem regardless of whether the city is bustling with life or lying in ruins. In the exact same way, God constantly surrounds His people. Even during difficult periods of strict judgment and long exile, He never abandons them [אלשיך]. This promise of divine guarding takes effect from the moment of redemption and remains unbroken for all eternity [מאירי].