Lamentations 1:21 (ESV)

21 “They heard my groaning, yet there is no one to comfort me. All my enemies have heard of my trouble; they are glad that you have done it. You have brought the day you announced; now let them be as I am.

Jerusalem realizes that what has happened to her is part of the Day of the Lord that was prophesied by Isaiah, Joel, Zephaniah, Amos, and Jeremiah. This “Day” was the time when God would judge his own people and the nations. Now Jerusalem prays that the rest of the Day will come: that God will also judge the other nations, just as he had promised (Jeremiah 46:1 – 51:64; Zephaniah 2:4–15).