Prime Minister Benjamnin Netanyahu said on Thursday that Israel was ready for two possible outcomes to the ongoing rocket fire from the Gaza Strip.

“One possibility is that the fire will stop and the quiet continues,” Netanyahu said. “The other is that the fire continues and then the increased forces that are in the south will act forcefully. The safety of our citizens is first and foremost.”

Netanyahu’s comments came as terrorists in the Gaza Strip continued to fire volleys of rockets at southern Israel.

Over 15 rockets were fired from the Gaza Strip Thursday evening, leaving one soldier lightly injured.

Palestinian sources said Israel had issued a 48-hour ultimatum to Hamas to halt the fire or face a massive Israeli strike. The ultimatum was conveyed to Hamas leaders via Egyptian intelligence, they said.

An hour before the evening rocket barrage, Hamas said that in the event of an escalation, Israel would “be surprised” by its rocket arsenal and range.

“We promise that one stupid move your leaders make will constitute sufficient ground to turn all of your towns, even those you wouldn’t expect, into targets and burning cinders,” said Abu Ubaida, a spokesman for the Izz ad-Din al-Qassam Brigades, Hamas’s armed wing. Israel may initiate the escalation, “but it doesn’t know how it will continue and how it will end,” he said.

The IDF beefed up its ground forces around the Gaza Strip on Thursday, as tensions continued to rise along the southern border region; and in East Jerusalem, where the recent killing of a Muslim teenager, in an alleged revenge attack over the killings of three Israeli teens, triggered widespread riots on Wednesday.

Israel’s cabinet, meanwhile, has remained mum on possible anti-Hamas operations in the wake of the kidnapping and murder of the three Israeli teens by Hebron-based Hamas members.

Whether or not a larger IDF operation is imminent, the build-up is a message to Hamas — under pressure from the shuttering of its border with Egypt, a multi-year siege on its Israeli border and a collapsing economy in the Strip — that escalation could spell significant damage for Gaza and its rulers.

Rocket fire from Gaza damaged two buildings in Sderot on Thursday morning. No injuries were reported. One of the rockets hit the side of a building that served as a preschool, but did not explode.