Israel warned on Tuesday that Hamas was "playing with fire" shortly after Gaza militants fired a Grad rocket into the coastal city of Ashkelon.
"Hamas is playing with fire, and if there is going to be an escalation now, Hamas has no one to blame but itself," said Mark Regev, Prime Minister Ehud Olmert's spokesman.
The Grad that struck Ashkelon was the first such rocket to be fired at the city since a cease-fire ended Israel's 22-day offensive in Gaza last month.
Three people were treated for shock after the attack, which also caused damage to property.
Regev added: "Hamas has acted to deliberately undermine the calm."
During his visit to the site of the rocket attack in Ashkelon on Tuesday, Likud chairman Benjamin Netanyahu vowed to "topple the Hamas regime" in Gaza if elected prime minister.
"When we said a few years ago that missiles will fly in the direction of Ashkelon, Tzipi Livni and Kadima mocked us," Netanyahu said. "In recent years, Kadima's policy of blindness has brought us to where we are today. Ashkelon residents cannot trust Kadima. We need a change in policy."
The former premier noted that the way to confront the rocket threat is solely through military means.
"We need to topple the Hamas regime in Gaza," Netanyahu said. "The Likud led by me will act to bring down Hamas and remove the threat of missiles against the south."
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