KFAR SIRKIN, Israel — Israel is building another wall to protect itself from its enemies. But rather than a major eyesore, much of this one will be invisible.

In the coming months, military officials say, the army will be accelerating construction of a subterranean barrier around the Gaza Strip, designed to cut off tunnels running beneath the border into Israel like the ones Hamas militants used to ambush Israeli military posts during the summer-long war of 2014.

Challenged by hostile forces on most of its fronts, Israel is already pretty much walled in. Aboveground fences and sections of concrete wall run along and through parts of the West Bank, a legacy of Palestinian suicide bombings during the second intifada. Formidable steel fences also stretch along the northern frontiers with Lebanon and Syria, the southern borders with Jordan and the Egyptian Sinai, and around Gaza, the isolated Palestinian coastal enclave controlled for the past decade by Hamas, the Islamic militant group.

The approach seems to have caught on internationally. President Trump invoked Israel’s “wall” — without specifying which one — as a model for the barrier he has vowed to build along the United States’ border with Mexico. And the migrant crisis has spurred European interest in Israeli fence-building techniques.