What is the meaning of "ha'Sipol Tzipor Al Pach ha'Aretz u'Mokesh Ein Lah"?
Radak citing Ibn Ezra: A bird, which is not under man's control to seize it ? will it fall in a net if there is no snare? Man, via strategy and cunning, can make a bird, which is above him, fall. I am above you, and you are below, in My hand. You have no Chachmah against Me. How can you be saved from the snare that I decreed against you, to trap you in it?! The Mokesh is the enemy that I will command to come against you.
Malbim: When a bird flying above falls into a trap, surely there is a snare to trap it.
Malbim (Yeshayah 8:14, Bi'ur ha'Milos): Pach is a trap that does not damage. Mokesh damages; it is what traps the prey.
Why does it say "ha'Ya'aleh Pach Min ha'Adamah [v'Lachud Lo Yilkod]"?
Rashi: Will the net rise from where it was placed, unless the bird was caught in it?! When it wants to flee it uproots the net and lifts it a little from its place ? it is already trapped! I.e. can you transgress, and it will not be a snare in which you are caught?!
Radak: This is another Mashal. The enemy will not depart from you empty (without killing or taking captives).
Radak citing Ibn Ezra: Do not think that after the enemy comes, he will depart, for he will not depart from you until he takes vengeance from you, for I will stand him up to pain you!
Malbim: When we see the trap rise, surely it trapped something! This is an introduction to verse 13 and onwards ? Yisrael were trapped in the hand of Melech Ashur. There is a reason why he was the snare!