Israel and Lebanon have officially approved a historic United States-brokered agreement laying out their maritime boundary for the first time, which opens up the possibility for both countries to conduct offshore energy exploration.

Lebanon’s President Michel Aoun signed a letter at the presidential palace on Thursday morning that will be submitted to US officials at Lebanon’s southernmost border point of Naqoura later in the day.

Top Lebanese negotiator Elias Bou Saab said the deal, which ends a long-running maritime border dispute in the gas-rich Mediterranean Sea, marked the beginning of a “new era”.

Israel’s government also ratified the agreement on Thursday, a statement from Prime Minister Yair Lapid’s office said.

Lapid said the deal was a “political achievement” for Tel Aviv as “it is not every day that an enemy state recognises the State of Israel, in a written agreement, in front of the entire international community”.

The agreement comes after months of indirect talks mediated by Amos Hochstein, the US envoy for energy affairs, and the deal was welcomed by US President Joe Biden.

“[The agreement] will secure the interests of both Israel and Lebanon, and it sets the stage for a more stable and prosperous region,” Biden said in a statement, before adding that the Middle East was “one step closer” to being more “integrated”.

The two countries have no diplomatic relations and have formally been at war since Israel’s creation in 1948.

Beirut has sought to avoid framing the agreement as normalisation with Israel, insisting that another annexe scheduled to be signed by both sides at the UNIFIL headquarters in Naqoura later on Thursday be signed in separate rooms.

Aoun countered the Israeli claim that the deal meant that Lebanon had implicitly recognised Israel. “Demarcating the southern maritime border is technical work that has no political implications,” Aoun said.

Hassan Nasrallah, the leader of the Iran-backed Lebanese armed group Hezbollah, said that the Lebanese government had been wary of carrying out any actions “that even smelled of normalisation” with Israel. Nasrallah also announced an end to Hezbollah’s mobilisation of its forces after the agreement was signed.

Hezbollah had threatened attacks against Israel if the latter unilaterally began gas production before a deal was agreed.

Economic opportunity

With the Lebanese economy in complete collapse, Beirut sees the demarcation of the maritime border along Line 23 as an opportunity to unlock foreign investment and lift the country out of its spiralling economic crisis.

Lebanon’s foreign minister Abdallah Bou Habib told Al Jazeera that “the Lebanese people have great hope that their country will become a gas-producing country”.

He noted, however, that it will take time for Lebanon to begin extracting gas and that gas reserves in its offshore reservoir have yet to be proven.

Bou Habib confirmed reports that the Lebanese government had awarded French oil firm TotalEnergies temporary control of a previously disputed offshore gas block.

“TotalEnergies and its partners must start work in the areas agreed upon with the Lebanese government, namely block Number 9 in the Qana field,” he said.

Under the terms of the deal, Israel received full rights to explore the Karish field, which is estimated to have natural gas reserves of 2.4 trillion cubic feet (68 billion cubic metres).

In turn, Lebanon received full rights in the Qana field but agreed to allow Israel a share of royalties through a side agreement with the French company TotalEnergies for the section of the field that extends beyond the agreed maritime border.

Critics of the deal have said it does little to address the issue of profit distribution but defers agreeing on what royalties Israel will get from the Qana field to a future date.

Al Jazeera’s Zeina Khodr, reporting from the Lebanon-Israel border, said all parties had vested interest in the securing a deal at this point in time.

“For Lebanon, this is about the economy. It is hoping that it can begin exploration for much-needed revenues, but many warn it will be years before it can reap the benefits,” she said.

Israel’s Lapid was instead looking for security guarantees, Khodr said, both to shore up support ahead of a general election on November 1 and “to increase production in Karish to get gas to Europe as an alternative to Russian gas.”