The United Nations has signed a temporary agreement with Israel and the Palestinian Authority, or PA, to allow reconstruction work to begin in the war-ravaged Gaza Strip, Robert Serry, the U.N.’s Special Coordinator for the Middle East Peace Process, said on Tuesday.

“UNSCO (U.N. Special Coordinator for the Middle East Peace Process) has brokered a trilateral agreement between Israel, the Palestinian Authority and the U.N. to enable work at the scale required in the Strip, involving the private sector in Gaza and giving a lead role to the Palestinian Authority in the reconstruction effort,” Serry said, briefing the Security Council on the situation in the Gaza Strip.

Serry also added that the agreement would provide “security assurances through U.N. monitoring that these materials will not be diverted from their entirely civilian purpose,” addressing Israel’s concerns that construction material was being used to build and fortify Hamas’ “terror tunnels.”

The announcement was made just three weeks after a cease-fire, brokered by Egypt, was reached between Hamas and Israel, ending a 50-day war that left over 2,100 Palestinians and 71 Israelis dead. 

In his statement, Serry expressed concerns that the cease-fire, which has largely held since Aug. 26, remains “worryingly fragile,” and that Gaza could “implode, or explode again.”

Describing the destruction of infrastructure, hospitals and schools in Gaza as “shocking,” Serry said that the conflict had left large neighborhoods in Gaza in “total ruin” and that an estimated 18,000 houses were destroyed or severely damaged, leaving nearly 100,000 people homeless. 

Palestinian President Mahmoud Abbas had earlier reportedly said that the reconstruction work in Gaza would cost nearly $7.8 billion, which is two and a half times Gaza's gross domestic product.