Hamas is redirecting building supplies, intended for rebuilding infrastructure damaged during Operation Protective Edge, towards rebuilding its network of terror tunnels instead, Israeli news sources reported Friday. The claim was bolstered by remarks from Prime Minister Benjamin Netanyahu and Defense Minister Moshe Ya’alon Saturday night.

Ynetnews reported Friday that sources inside the Gaza Strip informed them of the tunnel activity, in addition to other abuses of materials sent for civilian use. According to the news agency, “dual use” materials, such as iron, are being appropriated to replenish Hamas’ arsenal of rockets, severely diminished by this summer’s military engagement.

Hamas has also learned the lessons of the conflict, the report claims. Following the relative success of its tunnels, Hamas has invested in their reconstruction. Since Israel’s Iron Dome technology is most effective against medium-range rockets, the terror group is focusing its energies on its short-range rockets, for which Israel has no defense system as yet. It has conducted several test launches into the sea in recent weeks, as well.

Hamas is being careful not to divert cement earmarked for the rebuilding efforts for its cause, however, other materials, such as concrete, are being taken. The materials themselves are being allowed into the Gaza Strip by Israel in limited quantities, and have been since October, on condition of strict supervision. Prior to that, a heavy blockade was in place against the Strip, both from Israel and neighboring Egypt. Other materials are being smuggled in illegally.

Speaking at a candle-lighting event for Israeli soldiers in honor of the Hanukkah holiday Saturday night at the Western Wall in Jerusalem, Ya’alon addressed an Israeli Air Force strike on Gaza. It came in response, he said, to rocket fire from Gaza Friday, which aimed at Israeli civilians. The strike, he explained, targeted a Gaza concrete factory being used to rebuild the tunnels.

“We hold Hamas responsible for what happens in Gaza, and will act forcefully against it if it won’t prevent attacks at Israel,” Ya’alon said.

Netanyahu had a similar message. “Israel’s security comes first and I will not overlook even one rocket fired at Israelis,” Netanyahu said. “The Air Force responded by firing on a concrete plant which was used to rehabilitate terror tunnels destroyed in Operation Protective Edge.”

“Hamas will be held responsible for any escalation to come,” he warned. “We will guard Israel’s security.”

There has been a significant reduction in rocket fire since the summer engagement and subsequent ceasefire, and the establishment considers Operation Protective Edge to have been a success.

Friday’s incident marks the third time rockets have been fired into Israel since the August ceasefire. 4,500 rockets and other projectiles were launched into Israel before and during the operation.