After more than three decades of peace between Israel and Egypt, relations are fraying. A cross-border attack last month left five Egyptian police officers dead. Protesters last weekend stormed Israel's embassy. This week, most Israeli diplomats fled Egypt. Things have gotten so bad that Egypt's prime minister this week said even the 1979 peace treaty wasn't sacred. NPR's Soraya Sarhaddi Nelson joins host Scott Simon from Cairo to talk about the latest there.