Lebanese militant group Hezbollah has threatened to launch anti-ship missiles at Israeli-operated gas infrastructure at the Karish gasfield in the Mediterranean.
The gasfield has been at the centre of a dispute over the two countries’ maritime borders, with negotiations between Israeli and Lebanese delegations failing to reach a compromise on the disputed stretch of ocean.
The threat came a US envoy appointed as a mediator in the talks arrived in Beirut, reportedly with a new proposal to manage the disputed area. Amos Hochstein met with senior government officials including President Michel Aoun and Energy Minister Walid Fayad.
"Reaching a resolution is both necessary and possible, but can only be done through negotiations and diplomacy," the US State Department said in a statement ahead of Mr Hochstein's visit.
The issue has been highly sensitive in Lebanon, with Mr Aoun warning last month that “any activity or action in the disputed area is considered a provocation and aggressive act.”
A drilling vessel was sent to Karish in June, operated by Energean, an Israeli-British venture. Wells could be operational by September.
In June, Hezbollah were accused of sending unarmed reconnaissance drones to monitor operations at the site. Lebanese Foreign Minister Abdallah Bou Habib criticised the drone mission, saying any actions “outside the state's framework and diplomatic context,” would create “unnecessary risks.”
Last week, Hezbollah leader Hassan Nasrallah warned that his country’s government was “incapable of making the right decision that would protect Lebanon and its riches, therefore the resistance must take this decision.”
But the latest video represents an explicit threat, portraying a mock attack on the infrastructure using anti-ship missiles that analysts say are supplied by Iran.
Hezbollah is thought to possess a number of Chinese-made C-802 anti-ship missiles that have been upgraded by Iran. The group used two of the weapons during the 2006 Israel-Hezbollah war, seriously damaging an Israeli warship and killing four crew members.
Lebanon and Israel are locked in US-mediated negotiations to delineate their shared maritime border that would help determine which oil and gas resources belong to which country and pave the way for more exploration.
Lebanese officials have said they are optimistic that this round of talks can result in a deal after years of on-and-off indirect negotiations, but Hezbollah has warned it is ready to prevent Israel from extracting hydrocarbons should Lebanon not be allowed to do the same.
Sunday's video, which also contains a rare glimpse of Hezbollah weaponry, was broadcast on the group's Al-Manar TV station hours before the US official mediating the maritime dispute, Amos Hochstein, was scheduled to meet Lebanese officials in Beirut.
It was issued by Hezbollah's War Media that the group uses to broadcast footage of military operations and battles, and contains images of ships involved in drilling for and extracting hydrocarbons, along with what appear to be their co-ordinates.
The video begins with the words of Mr Nasrallah during a recent speech in which he warned that “playing with time is not useful” on the maritime issue.
“The message is a serious threat,” a top Al Manar correspondent said on Twitter.
A statement on Saturday by the US State Department said Mr Hochstein's Beirut visit would aim to facilitate talks on the maritime boundary.
“Reaching a resolution is both necessary and possible, but can only be done through negotiations and diplomacy,” it said.
A senior Israeli official told Reuters that Mr Hochstein would represent a new Israeli proposal that “includes a solution that would allow the Lebanese to develop the gas reserves in the disputed area while preserving Israel's commercial rights”.
If this reaches agreement, it would entail “some drilling there” by the Lebanese, the unnamed Israeli official said, without elaborating.
“The offer that has been relayed is a serious proposal that can transform Lebanon from a country of economic ruin and energy crises to a natural gas-producing country, by enabling it to cultivate this resource,” the official said.