JERUSALEM — Israeli Prime Minister Benjamin Netanyahu vowed revenge Friday for what he described as a “cruel and malicious violation” of the ceasefire agreement after authorities determined that a body released by Hamas as part of the deal was not an Israeli mother of two small boys, as the militant group had promised.

Israel's prime minister accused Hamas on Friday of killing two Israeli children in Gaza and said the militants would pay for failing to return their mother, Shiri Bibas, which Hamas blamed on a possible "mix-up" of bodies.