Israeli warplanes on Tuesday bombed smuggling tunnels on Gaza's border with Egypt after the Jewish state warned of the "severest riposte" to rocket fire from the Hamas-run enclave, witnesses said.
There were no immediate reports of injuries.
Speaking at a security conference in Herzliya, north of Tel Aviv, Defence Minister Ehud Barak said: "I suggest Hamas doesn't fool around with us."
"The air force is operating in Gaza as we speak. We promised calm in the south and we will keep our promise." - Sapa-AFP