A mirror can only reflect what is there, so what happens when there's nothing left to reflect? In lines 22-25, the second speaker uses mirror imagery to contrast Vietnam before the bombings and war to Vietnam after the bombings and war. The speaker first mentions that, in pre-war times, "peaceful clouds" may have been reflected in the water. But, after the bombs, those "mirrors" were smashed. Here, the mirror is a symbol for the loss of existence. There's nothing left to see, after this total destruction; there's no peace, no anything, left to cast a reflection.