In what stands to be a massive project, Israel’s Southern Command has begun the construction of a “huge barrier around the Gaza Strip,” which is going to include multiple fences and walls on the surface, as well as underground barriers to try to prevent tunnels being dug.

The surface-level fences and walls are said to mirror what Israel built on the Egypt border, but the underground effort is something new, and exactly how much it’s going to cost is unclear. Despite not having the money appropriated, the project has begun.

Estimates have put the cost at around $800 million, with some even higher. The existing border fence appears to have been working fine, beyond the occasional report of a tunnel from Gaza into Israeli territory. Those tunnels, however, have been huge news in Israel, and parlayed by the military for more funding in the area around Gaza.

Israel strictly limits traffic into and out of the Gaza Strip, and also imposes a naval blockade on its coast, preventing ships from delivering aid. The Gaza airport was destroyed by Israel in 2001, and Israel’s ally, the Egyptian military junta, has built its own steel fence sealing off the Strip.