Iran Beefs Up Defenses, Recruits Children as It Prepares for Ground War

Tehran promises an all-out fight if the U.S. invades, including new attacks on the Gulf.

Iran is responding to the threat of a ground operation on its soil by stepping up defenses around its biggest oil port, while threatening to attack a wider array of targets around the Gulf and launching a mass recruitment drive reminiscent of its 1980s war with Iraq.

Military analysts say Iran has around one million active and reserve troops.

The steps come as President Trump has ordered thousands of Marines and Airborne troops to the Middle East. While the president hasn’t said he plans to put boots on the ground, the deployments

A satellite view of Iran's Kharg Island.

Military analysts say tunnels have likely been carved into many of the islands, which Iran is preparing to defend with missiles and other munitions. Iranian-backed militias in Iraq have demonstrated the use of wire-guided first-person view drones, which are possessed in greater numbers by Iran’s Islamic Revolutionary Guard Corps, posing a potent threat to any U.S. troops.

The regime has signaled its defense will also involve spreading more pain around the region to dramatically raise the price of any attack. Tehran, which has successfully shut off most Gulf oil exports and hit facilities and airports, has told its neighbors it would expand its targets to offshore oil platforms if its islands are invaded, Iranian and Arab officials said. It has also threatened to hit vital infrastructure like power plants and desalination facilities.

“Iran intends to make any U.S. landing as costly and politically unsustainable as possible,” said Sanam Vakil, director of the Middle East and North Africa program at Chatham House, a London-based think tank. “I expect Iran will try to swarm and inflict pain through drones first and then widening its retaliation to its neighbors.”

Military analysts, including the New Lines Institute for Strategy and Policy in Washington, say Iran has around one million active and reserve troops. Among them are around 190,000 of the Islamic Revolutionary Guard Corps’ motivated fighters.

While the bulk of the country’s forces are undertrained and equipped with inadequate arms that sometimes date back decades, they have the benefit of Iran’s mountainous terrain and years of working with regional militias in asymmetric fights against Israel and the U.S.

Forces deployed along Iran’s coastline have more extensive exposure to armed operations than those in the country’s interior, which hasn’t seen direct combat since the war with Iraq.

Members of security forces look on during a funeral procession.

The Revolutionary Guard’s navy—which includes hundreds of small, fast boats armed with missiles, torpedoes and mines—has for years harassed vessels in the Persian Gulf and has intensified such attacks during the current conflict. In 2016, the Revolutionary Guard’s navy captured 10 U.S. sailors whose boats had steered too close to an Iranian island in the Gulf. It later released them unharmed.

Analysts weighing possible U.S. ground operations focus on an invasion of Kharg island, Iran’s main export terminal, in a move to seize the country’s oil. Other possible missions include taking Iranian islands in the Strait of Hormuz like Abu Musa, which is claimed by the United Arab Emirates, or a special forces raid to capture Iran’s stockpile of enriched uranium.

Chris Long, a former British Navy officer in the Persian Gulf, says he expects Iran to launch ballistic missiles and drones from military sites it has on Qeshm island in the Strait of Hormuz or Bushehr, the closest onshore port to Kharg, though it wouldn’t be limited to those launch sites. Missiles targeting U.S. forces on Persian Gulf islands could be fired from almost anywhere in Iran, he said.

On the islands and from the nearby shores, Iranian troops in fortified tunnels would pound invading forces with cheap FPV drones and shoulder-mounted air defense missiles, said former Russian air force officer Gleb Irisov, who worked closely with Iranian forces when he was deployed in Syria.

“There are no half-measures there,” Irisov said. “The U.S. needs to land over 100,000 troops on the whole shoreline to defend and protect these islands and the strait. All other ways will end up in massive American casualties.”

Any U.S. operation to seize Iranian islands is more likely to further destabilize the Strait of Hormuz than secure it, said Mohammad Hassan Sangtarash, a Tehran-based defense analyst close to the Iranian government.

The government is also tightening up the home front. A resident in Isfahan said balaclava-clad security forces had set up new checkpoints in the central Iranian city and nearby towns over the weekend.

On Sunday, Iran launched a campaign called “Janfada,” or “Sacrifice,” to recruit volunteers to fight American forces, according to a text message sent to mobile subscribers in Iran. The Revolutionary Guard also says it is conducting a campaign to recruit volunteers as young as 12 to provide support services like cooking and medical care as well as to man checkpoints.

Defa Press, which is affiliated with Iran’s Defense Ministry, published a recruitment poster featuring a teenage boy and a veiled girl, both smiling. The U.S.-based nonprofit Human Rights Activists in Iran says it has received reports of children killed while staffing checkpoints.

“Given the enthusiastic welcome of the dear people, we decided to create an environment where all interested parties can play a role in defending the homeland based on their expertise and capabilities,” Rahim Nadali, the Revolutionary Guard’s deputy director for Culture and Arts, told Defa Press.

It is hard to know how many Iranians would join such campaigns. Fars news agency, which is affiliated with the Revolutionary Guard, put the total in the millions so far. Whatever the number, an invasion is likely to draw a nationalist response from across the country’s divided population.

“Some high-risk poker is at play here,” said Bob Harward, a retired Navy SEAL and a former deputy commander of the Central Command, which oversees the Middle East.

Azam Jangravi, an activist who fled Iran after protesting against the compulsory veil, said she initially favored the bombing campaign that targeted Iran’s leaders and security forces. But she said she changed her mind after Trump threatened to occupy Iranian islands.

“Territorial integrity is a red line for most Iranians, whether they support the regime or oppose it,” she said.

Write to Benoit Faucon at benoit.faucon@wsj.com