Nearly four weeks of fighting in Iran has slowed the pace of ballistic missile launches targeting Israel compared with the early days of the fighting - but for several weeks now the Iranians have been firing an average of 10 to 15 missiles a day on a regular basis, in what appears to be a carefully calibrated strategy in use of its weaponry.

One reason for Iran's resilience, despite the destruction of half of its launchers and ballistic missile stockpiles, is a result of the way its fortified missile bases were built over decades deep underground.

According to a CNN investigation earlier this week, the Revolutionary Guards have dug nearly 30 underground missile cities carved deep into granite mountains over the past few decades, rich in concrete missile depots, dozens of exit tunnels connected by automatic trains and with pop-up doors that effectively protects them from air attacks, and even from ground invasion.

The investigation identified at least 27 such underground bases, including at least 107 tunnels with exits. According to the Alma Research Institute, which deals with geopolitics and Israel's security challenges, 77% of the openings were hit by Israeli and US aircraft in the first three weeks of the operation.

However, the investigation made a disturbing finding: within a day or two, engineering vehicles were identified near these entrances, engaged in their rapid restoration. One of the more better known missile bases near Yazd in central Iran was bombed twice during the opening week of the war and again last week, with the internal damage to the structure unclear. What are these missile cities and what can be done about them?

How deep are the bases?

Dr. Amichai Mittelman, a tunneling expert and senior lecturer in the Department of Civil Engineering at Ariel University, explains that according to open sources, including those published by the Iranians themselves, these are sites dug into the mountains at a depth of several dozen meters, sometimes even a hundred meters below ground level. "The mountains in Iran provide a level of protection 50-100 meters thick of rock that is hard to crack even by heavy bombs. Firing bunker-penetrating bombs like those dropped on the nuclear facilities in Operation Night Hammer in June, the GBU-57 bombs, would have difficulty penetrating the interior of the mountain and up to the height of the bases in such a scenario; Even in the firing configuration that was made over the Fordow facility, in which another bomb was fired into the same hole created by the first bomb," says Mittelman.

Why is firing at tunnel openings not very effective?

Air Force planes are attacking the tunnel openings in an operation that the IDF spokesman calls "jamming the launchers." According to Tel Aviv University INSS data, as of the beginning of the week, about 200 Iranian missile launchers had been destroyed, and 135 had been destroyed that could return to service if the Iranians restored the destruction site. Another 120 launchers remained unharmed.

However, the Iranians also prepared for this scenario in advance - they built many exit openings for each of the missile cities, so that when one exit opening is disabled, trains loaded with missiles are diverted to other openings. In each of the missile cities, many dummy openings were built that do not actually lead into the tunnels, and other openings were built in camouflage, so that they appear to be a natural part of the mountain's contours. Finally, the facilities usually include heavy engineering teams within the complexes, who assist in the restoration of the openings in the days following an IDF attack.

Can missiles be launched from underground?

As early as 2020, Iran unveiled an advanced ballistic missile launch system, in which vehicles take ballistic missiles from storage and prepare them for launch directly from shafts located deep in an underground system that is immune to air strikes and devoid of any external signature. That same year, Tehran revealed the ability of an underground launch of the Emad missile, which has a range of 2,000 kilometers.

By using a combination of railways and lifting and launching facilities, the Iranians can, according to their reports, launch five missiles one after the other from each shaft. However, in the current operation there is no evidence of underground launches. The missiles fired at Israel are loaded onto a truck-like launcher, taken out of the underground complex and fired into the open air within a few minutes, which creates some kind of weak point for the Iranians.

"The Iranians, who call the current campaign "True Promise 4," release videos for each of their waves of attacks against Israel.

"However, so far, neither in the 2024 attacks nor in the two operations in Iran has there been any such documentation (of an underground launch)," notes Tal Inbar, an expert on the Iranian missile program and a senior research fellow at the Missile Defense Advocacy Alliance (MDAA). "The assumption is that if such a launch had taken place, the Iranians would have exploited it for public relations."

Are the ventilation holes and electrical infrastructure weak points?

"The Iranians thought of everything, so they built many ventilation holes and shafts and installed fans to compress the air inside," says Mittelman.

"Sometimes this is a weak point for underground complexes - suffocation of those inside, but it is doubtful whether this is true for the large missile cities. The electrical infrastructure is also built on backups."

Are the missile cities impenetrable to ground units?

"The underground bases include many bends, trap doors, massive walls and defense systems that even if you throw heavy weapons inside, it will not cause a chain reaction," says Inbar. "The effectiveness of a ground unit in such a facility is limited, and if you really want to solve the problem, you will have to send such a unit to each of these dozens of bases, which means it will be very difficult to succeed." Mittelman adds: "These are facilities that were built over years to the design of Iran's best engineers who thought of every scenario."

Published by Globes, Israel business news - en.globes.co.il - on March 26, 2026.

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