Over four years after a team of Hamas commandos entered Israel from the sea during the Gaza war of 2014, Israeli engineers are nearing completion of a smart sea barrier meant to prevent future attacks, Channel 10 news reported Monday.

Construction of the 200-meter-long barrier was carried out by the Defense Ministry off the beach of Zikim, on Gaza’s northernmost border. Work took seven months.

The barrier is meant to close a gap in Israel’s defenses along the border with Gaza.

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On land, Israel has an above-ground fence and is constructing a complex system of underground barriers and detectors to prevent Hamas — the Islamist terror group that rules Gaza and seeks to destroy Israel — from tunneling into Israeli territory. At sea, the Israel Navy maintains a permanent presence that is able to detect attempts to infiltrate Israeli waters.

But a gap existed just off the beach at Zikim, in the narrow area of shallow water where neither ground forces nor seagoing vessels could operate with ease.

Hamas commandos took advantage of that gap in 2014, easily bypassing an obsolete, dilapidated fence and crossing into Israel via the shallow waters.

The Hamas force was only stopped when IDF surveillance crews noticed their movements as they came onto the beach inside Israel.

The barrier is composed of several parts. An undersea wall of boulders stretches some 200 meters into the sea. Inside the boulder wall is a concrete wall lined with seismic detectors and other technological tools whose exact function is classified.

Above the water, along the western side of the north-south wall, a smart fence bristling with detectors rises to a height of six meters (20 feet).

On the eastern side, a breakwater with a road down the middle stretches the length of the underwater wall.

Construction was quick, despite being hampered on occasion by Hamas attacks.

In one such attack, a Hamas fighter shot and threw grenades at Israeli forces guarding the work crews, before being killed by Israeli return fire.