Israel has begun building an underwater sea barrier to prevent Palestinian infiltrators from entering Israel by sea, the Defense Ministry announced on Sunday.

Building began at the northern Gaza border, on Zikim beach. According to the Defense Ministry, the construction is expected to continue through the end of the year.

The barrier will consist of three layers. The first will be below the water; the second will be made of stone; the third will be made of barbed wire. An additional fence will surround the sea fence. The Defense Ministry described the barrier as "an impenetrable breakwater." It does not prevent Gazans from going out to sea.

"This barrier is one-of-a kind in the world," Defense cheif Avigdor Lieberman said. The barrier "Will effectively block any possibility of entering Israel by sea. This further thwarts Hamas, which is now losing another strategic asset after investing huge sums in its development," he said.

The state decided to erect a sea barrier during Operation Protective Edge in 2014, when several Hamas gunmen entered Israel by sea and were killed by the military.

The barrier is being built simultaneously with an inland underground barrier around the Gaza border.

Last year, The Israel Defense Forces announced they would begin construction on a massive barrier meant to stop the underground tunnels that Gaza built into Israel. The project, estimated to cost 3 billion shekels ($833 million), includes a concrete wall fitted with sensors and reaching dozens of meters deep into the ground and standing six meters high from ground level.