Why are the Lebanese army and Hezbollah simultaneously threatening Israel?

The Lebanese army has issued a threat against Israeli forces saying the military will use every possible means to confront Israel if necessary. The military's commander said his country stands ready to confront a potential "Israeli aggression" at any cost because Lebanon cannot compromise on its territorial rights.

"I affirm again our categorical rejection of the Israeli enemy infringing on Lebanon's sovereignty and its sacred right to exploit all its economic resources," the Lebanese army quoted General Joseph Aoun as saying in a statement shared via social media. "The army will not spare any method available to confront any Israeli aggression, whatever that costs."

His threat comes soon after the Lebanese militant group, Hezbollah, a Shia-oriented influential organisation, issued a similar warning against Israel. Making a televised address to rally, the extremist group's secretary-general, Hassan Nasrallah claimed that Hezbollah has enough power to stop some of the Israeli operations if it wants.

"If the Lebanese Higher Defense Council makes an official decision that some gas and oil rigs in the Palestinian sea – a sea plundered by Israel, the enemy entity – must not operate, I promise you that within a few hours, they will not operate anymore," said the Hezbollah chief as the gathered crowds chanted back: "We respond to your call, Nasrallah".

Hezbollah's threat was directed at the oil and gas rigs operated by Israeli forces while the warning issued by the Lebanese military emerged from the closely linked matter. The dispute between the Lebanese and Israeli militaries stem from a border being constructed by the Israeli Defense Forces (IDF).

While Israel says the wall is being built in its own territory at the frontier portions between the two countries, Beirut is contesting these claims saying the construction intrudes in its areas. Both sides have held talks with high-ranking officials participating but the negotiations have not yielded any result. US officials are also moderating the discussions.

Centre of the territorial dispute was the Blue Line drawn by the UN at the border when Israeli side pulled back its forces in 2000.

Meanwhile, the UN chief has expressed concerns that a potential confrontation between Israel and Hezbollah would be a "nightmare" in the region and will have serious consequences. Secretary-General Antonio Guterres said though there are no signs to indicate a full-fledged war could break out in the region "sometimes a spark is enough to unleash this kind of a conflict".

"I am deeply worried about hard-to-foresee escalations in the whole. The worst nightmare would be if there is a direct confrontation between Israel and Hezbollah ... the level of destruction in Lebanon would be absolutely devastating, so there are major points of concern around this situation," said Guterres while speaking to reporters in Lisbon.