The Assyrian army commander engages in a calculated campaign of psychological warfare against the residents of Jerusalem. He distills his argument into a clear warning: the people must not place their trust in their own military capabilities, nor should they rely on God [מלבי״ם]. The core of his message is specifically designed to undermine the reassuring words of the King of Judah.
The primary approach among commentators is that the Assyrian commander accuses Hezekiah of actively misleading, inciting, or enticing the people [רש״י, מצודת ציון, ביאור שטיינזלץ]. However, a subtle psychological distinction is noted regarding the exact nature of this deception. While general incitement attempts to convince someone of the practical benefits of an action, and seduction preys on a listener's innocence through smooth talk, the specific manipulation alleged here operates differently. It is a tactic used when a person is gripped by fear and hesitant to act; the persuader steps in specifically to soothe that anxiety and strip away the dread from their heart [מלבי״ם, שד״ל].
A classic example of this psychological manipulation occurred with the Tree of Knowledge, where the serpent deceived Eve by calming her and removing her natural fear of death [מצודת ציון, מלבי״ם]. In the same way, the Assyrian commander claims that Hezekiah is trying to erase the people's natural, justified terror of the massive Assyrian army. By offering false promises of military success, Hezekiah is attempting to calm their panic. The Assyrian warning is absolute: the King of Judah lacks the physical power to save the nation, and the people must not be led astray by his empty reassurances [מלבי״ם].