FORT LAUDERDALE, Fla. — In the fluorescent light of a Fort Lauderdale hotel meeting room, two grieving families of dead and kidnapped Israelis sat across mayors from South Florida and across the United States, pictures of their loved ones clutched in their hands. They had just arrived from Israel, where Natalia Casarotti’s 21-year-old son, Keshet, was killed at the Nova music festival, and ...