Why does it say "Ko Amar Hashem"?
Radak: This is from Hashem; He wants to destroy it. He aroused the enemy to come.
What is the meaning of "Kirsu Etzah"?
Rashi: Even though there is no Mapik (Dagesh, i.e. dot in the) Hei, this is an expression of Etz (trees). It cannot be Etzah (counsel), for cutting does not apply to it. It refers to many trees, just like Dagah refers to many fish. Radak - cut trees to make a bulwark and Solelah.
Malbim: Even though the Torah commands not to cut fruits trees when besieging a city to make a Solelah, lest they destroy the settlement - "Ki Mimenu Sochal" (Devarim 20:19), here it is opposite. The punishment is not only for the people, rather, also for the city itself.
What is "Solelah"?
Radak: It is catapult rocks 1 cast against the city to break the walls and towers.
Radak citing Targum Yonasan: It is a big mound. They pour earth and wood into the pits around the city, until they fill them in order to ascend on them against the wall.
Below (32:24), Radak explained that Solelos are the wood [machines] that cast rocks.
What is the meaning of "ha'Ir Hafkad"?
Rashi: Its [time for] punishment has come.
Radak: Its sin is being visited upon it. Even though Hashem delayed [punishing it], He will not delay more.
Malbim: The punishment is for the entire city to be destroyed.
Why does it say "Oshek b'Kirbah"?
Radak: Even inside the city they cheat, and all the more so outside.
Malbim: This is like "Ki Even mi'Kir Tiz'ak 1 " (Chabakuk 2:11)
Malbim (Chabakuk 2:11): The city was built with blood (of murdered people).
