JERUSALEM, Jan. 7 -- When thousands of heavily armed Israeli soldiers poured into the Gaza Strip on Saturday night, Hamas pulled back. Rather than stand and fight against the Middle East's strongest army, the Islamist movement opted for a tactical withdrawal, with its fighters melting away into the strip's sprawling cities and refugee camps, according to Gaza residents and Israeli military analysts and officers. Now, Hamas appears to be daring the Israeli troops to follow. "They're hitting here and there with antitank missiles and mortars. Overall, though, they're not confronting the Israeli presence in Gaza," said retired Gen. Amnon Lipkin-Shahak,...