Albert Barnes Commentary Lamentations 2:3

"He hath cut off in fierce anger all the horn of Israel; He hath drawn back his right hand from before the enemy: And he hath burned up Jacob like a flaming fire, which devoureth round about." — Lamentations 2:3 (ASV)

Since the horn is the symbol of power, the cutting off of every horn means depriving Israel of all power of resistance. The drawing back of God’s right hand signifies the withdrawal of that special Providence which used to protect the chosen people.

And he burned ... - Or, “and” he kindled a fire in Jacob: as the active enemy of “Jacob,” Himself applying the torch.