BEIRUT — Lebanon and Israel signed copies of a U.S.-mediated sea border deal on Thursday and delivered them to the U.N. in the coastal border town of Naqoura.

The agreement to demarcate the maritime border comes after months of indirect talks mediated by Amos Hochstein, the U.S. envoy for energy affairs, and would mark a major breakthrough in relations between the two nations, which have formally been at war since Israel’s creation in 1948.

Lebanon and Israel both claim around 860 square kilometers (330 square miles) of the Mediterranean Sea that are home to offshore gas fields. Lebanon hopes that demarcating maritime borders will pave the way for gas exploration to help lift it out of its crippling economic crisis, which has plunged three-quarters of its population into poverty. Israel hopes that the deal will reduce the risk of war with Lebanon’s Iran-backed militant group Hezbollah.

Lebanon and Israel sent delegations to the United Nations Interim Force In Lebanon, who received separately signed copies of the maritime border deal and confirmed coordinates from both countries.

U.S. President Joe Biden in a published statement Thursday said the deal serves the interests of both Lebanon and Israel.

“This agreement takes us one step closer to realizing a vision for a Middle East that is more secure, integrated, and prosperous, delivering benefits for all the people of the region,” the statement read.

Hochstein met with President Michel Aoun, caretaker Prime Minister Najib Mikati, and Speaker Nabih Berri earlier Thursday before heading to Naqoura. Following the signing, he headed to Israel to meet Israeli Prime Minister Yair Lapid.

“This agreement was written with the idea in mind that it was between two countries that don’t have diplomatic relations,” Hochstein told reporters at the Baabda Presidential Palace. “I think the good will and good faith efforts by all parties is what’s going to make this move forward.”

Lapid signed the agreement following Hochstein’s meeting with Aoun, according to a statement from his office.

“There is a rare consensus in all security systems on the importance of the agreement,” Lapid said. The Israeli Cabinet approved the deal in a special session. “This is also an economic achievement. Yesterday, gas production began from the Karish Platform.”

Tensions briefly flared between Lebanon and Israel last summer, after Israel began drilling in the Karish gas field as negotiations took place. Prior to the agreement, Lebanon considered the area to be disputed, while Israel said it was part of its U.N.-recognized exclusive economic zone.

Hezbollah leader Hassan Nasrallah briefly commented on the agreement in a televised address, and asserted that, contrary to what had been declared by some Israeli officials, its signing did not signal a recognition of Israel or the normalization of ties between the two states.

“We in Hezbollah consider that what happened from start to end to the results is a great, great victory for Lebanon, for the state, the people, and the resistance,” he said.

On the other side of the border, Lior Haiat, a spokesperson in the Israeli prime minister’s office, said, “This is a historic day. We have reached an agreement with an enemy country that will bring security to our maritime border, but it also brings benefits to Lebanon.”

It was not immediately clear when drilling will begin, but cash-strapped Lebanon is hoping French oil giant Total will start drilling early next year after both parties signed the agreement.

Under the agreement, the disputed waters would be divided along a line straddling the “Qana” natural gas field. Gas production would be based on the Lebanese side, but Israel would be compensated for gas extracted from its side of the line.

President Aoun earlier this month in a televised address announced Lebanon’s approval of the sea border deal. The Israeli Supreme Court rejected four legal challenges against the deal, after its government also approved the plan.

In 2017, Lebanon approved licenses for an international consortium including France’s Total, Italy’s ENI and Russia’s Novatek to move forward with offshore oil and gas development for two of 10 blocks in the Mediterranean Sea. Novatek recently withdrew and officials, including Energy Minister Walid Fayad, have said that Qatar is interested in filling that gap.

“I truly believe and hope this can be an economic turning point in Lebanon for a new era of investment and continued support to lift up the economy,” Hochstein said.

Lebanon has since reached out to Syria and Cyprus to start direct negotiations over their northern and western maritime borders as well.