JERUSALEM (Reuters) – Israel received its most advanced warship on Wednesday, describing the German-made vessel dubbed “Shield” as a bulwark for vulnerable Mediterranean gas rigs as tensions with Tehran soar over the assassination of a top Iranian nuclear scientist.

The Saar-6 corvette that docked in Haifa port, and three of the same model to follow next year, will bring to 15 the number of missile boats deployed by an Israeli navy which, while small, carries out missions as far away as the Red Sea and the Gulf.

Israel also wants to protect off-shore natural gas fields close to Lebanon, an old foe with which it has held so far fruitless U.S.-mediated maritime border talks.

“The welcome discovery of the gas fields off Israel’s shore made it necessary to create a plan that will provide a protective envelope,” Israeli President Reuven Rivlin said at ceremony at the port.

The navy sees a threat to the gas rigs from Lebanon’s Iranian-backed Hezbollah guerrillas, especially after Tehran vowed to retaliate for Friday’s killing of nuclear mastermind Mohsen Fakhrizadeh, which it blamed on Israel.

“The Iranians are looking for ‘prestige’ targets like these, that can be hit with low casualties, meaning—they may hope—less chance of escalation,” an Israeli security official told Reuters. “The question is whether Hezbollah would strike now.”

Though Hezbollah has previously threatened the gas rigs, it said responding to Fakhrizadeh’s death was in Iran’s hands.

Unlike earlier models of Israeli missile boats, the Saar-6 will be fitted with both electronic countermeasures for cruise missiles, which have a flat trajectory, and a maritime version of the Iron Dome system for shooting down high-angle rockets.

These, a senior naval officer said, are precautions against Soviet-designed Yakhont cruise missiles and Iranian-made Khalij Fars rockets that Israel believes are in Hezbollah’s arsenal.