As long as they don't send warships and try and invade Israeli waters they wont be fired on. But move out of the designated trapezoid that is gazan territorial water and they are then committing acts of war. The best they could manage would be a blow up two man boat because the sea is so shallow. Israel has its planes less than 2 minutes away from the area, shoot the boats in Israeli waters and they are no longer a problem.
UNITED NATIONS CONVENTION ON THE LAW OF THE SEA
Every State has the right to establish the breadth of its territorial sea up to a limit not exceeding 12 nautical miles, measured from baselines determined in accordance with this Convention.
With Gaza's permission, Russia can do whatever it likes in that area. Any Israeli attack would be an act of war.
Of course, Israel never looks at International law when it wants to ignore it.
A lot of gas in in the illegal security zone.
Question is - if Russia set up legal rigs in the Gaza gas field, would Israel dare to attack - illegal security zone or not?
Russia would be legally entitled to defend against any attack, and destroy enemy forces, even if they'd returned to Israel.
If it went that far, would America attack Russian forces, potentially starting WWIII?
Big bets are on the table.