The United States-Russian deal for the destruction of Syria's huge chemical weapons stocks caused Israelis to breathe an audible sigh of relief. Many expected that a U.S. strike would push either Syria or its ally Hezbollah tio retaliate by attacking Israel. Over the past few weeks, thousands of Israelis, not known for their patience, spent hours waiting in line for government-issued gas masks. Yet the deal also increases pressure on Israel to get rid of its chemical and, even more troubling to the Jewish state, its nuclear stockpile. If Syria must get rid of its chemical weapons, the reasoning goes,...