Keil & Delitzsch, on Lam 2:5

The Lord has become like an enemy. כּאויב is not separated from היה by the accents (Pesik and Mahpak before, and Kadma after); so that there appears to be nothing to justify the remark of Gerlach, that, "as if the prophet were hesitating whether he should state explicitly that the Lord had become an enemy, he breaks off the sentence he had begun, 'The Lord hath become...,' and continues, 'He hath destroyed like a mighty one.' " As to בּלּע, cf. Lam 2:2. "Israel" is the name of Judah viewed as the covenant people. The swallowing or destruction of Israel is explained in the clauses which follow as a destruction of the palaces and fortresses. The mention of the palaces points to the destruction of Jerusalem, while the "fortresses" similarly indicate the destruction of the strong cities in the country. The interchange of the suffixes ־יה and ־יו is accounted for on the ground that, when the writer was thinking of the citadels, the city hovered before his mind; and when he regarded the fortresses, the people of Israel similarly presented themselves. The same interchange is found in Hos 8:14; the assumption of a textual error, therefore, together with the conjectures based on that assumption, is shown to be untenable. On the expression, "He hath destroyed his strongholds," cf. Jer 47:1-7 :18; on תּאניּה ואניּה, Isa 29:2 : in this latter case, two word-forms derived from the same stem are combined for the sake of emphasis. "Daughter of Judah," as in Lam 2:2, cf. Lam 1:15.