Following the outbreak of open hostilities between between Israel and militia groups based in the Gaza Strip on Oct. 7, the Israel Defence Force’s (IDF) invasion of the Palestinian territory which began 20 days later has faced serious difficulties tackling local militias operating from underground tunnel networks. Israel has for well over a decade sought to minimise the ability of Palestinian militia groups, including the forces of Gaza’s ruling authority Hamas, to build underground fortifications. Since 2007, it has imposed a blockade of the territory that has specifically targeted construction materials which could be used for this purpose. The success of these Israeli efforts has been limited, however, with the IDF having reported a decade ago that one underground network alone was 2.4 kilometres in length, 20 metres below the surface, and featured 350 tons of concrete in its construction. More recently senior Israeli officials have stated that there are some 5,700 separate shafts leading to the network, which is between 350 and 450 miles (560 and 725km) long. With Gaza itself being just 140 square miles (363 square km) in size, this represents a very significant degree of fortification. On Jan. 16, the New York Times reported that the IDF had been “astonished” by the size of the network, with Israeli officials estimating that it could take “years” to disable it.
Regarding the utility of the tunnel networks used by Palestinian militia groups, not only do they provide cover from many kinds of surveillance, but they also force Israel to expend costly and relatively scarce “bunker buster” munitions to engage targets. Footage released by militia fighters under Hamas and Palestinian Islamic Jihad has also shown combatants making use of the tunnels to redeploy in teams behind Israeli lines, throwing grenades into groups of resting personnel or flanking Israeli armour to destroy it from close ranges using rocket-propelled grenades and other explosives. The tunnels have thus served as a major force multiplier in one of the most unbalanced conflicts in the world in terms of technology, firepower and manpower, allowing militia groups otherwise far from outstanding in their capabilities even by the standards of the Middle East’s many non-state forces to engage a leading regional military. Largely as a result, the latest reports from U.S. intelligence officials indicate that four months into the war, and having suffered increasingly serious economic losses and growing war fatigue, Israel is not close to achieving its goal of eliminating the little military power Hamas had.
The effectiveness of tunnel networks under Gaza for military purposes is particularly notable when considering that the network itself is far inferior to that deployed across Israel’s northern border by the Lebanese militia group Hezbollah. The tunnel and bunker network in the region south of Lebanon’s Litani River alone was, by 2006, estimated to have fortified command bunkers constructed to a depth of 40 meters using poured concrete, and over 600 ammunition and weapons bunkers fortified eight or more meters underground. This network was, according to Western and Israeli sources, constructed using North Korean technologies and with planning and supervision from Korean specialists who deployed to Southern Lebanon. Aside from the presence of Korean specialists, not only was southern Lebanon not under blockade, but the rock-hard soil in southern Lebanon was far more suitable for building tunnel networks compared to the much softer coastal soil in Gaza. The two networks were thus incomparable in their defensive value. This bodes ill for any potential Israeli invasion attempt of Southern Lebanon, reportedly currently under consideration, considering its forces’ struggles against the far inferior Gazan network.
Since the 2010s, the tunnel network in the Gaza Strip has been widely speculated to have benefitted from North Korean tunnelling methods and technologies, likely passed on by the sponsors of local militia groups namely either Iran or Hezbollah, but possibly provided with some input from Korean specialists directly. As observed by Victor Cha, former director for Asian affairs at the White House National Security Council, in 2014: “Hamas’ vast tunnel network almost certainly benefited from outside assistance, whether directly from North Korea or via Iran,” highlighting that cutting off this support was key to achieving the U.S. and Israeli objective of disarming the territory. It is similarly uncertain whether North Korean anti-tank weapons reported to now be widely used against Israeli forces were supplied directly or through Hezbollah or Iran, which the country is known to supply weapons to, with denials by Pyongyang indicating that the latter may be more likely. Nevertheless, with the tunnel network in Gaza being extremely limited compared to that built under southern Lebanon, let alone that under North Korea itself which is considered likely the greatest in the world, much can be extrapolated from Israel’s struggle in its current conflict regarding the difficulties an invasion of either Southern Lebanon or North Korea would pose. The former was attempted by Israel in 2006 and failed largely due to Hezbollah’s effective use of its underground network, while the latter has been seriously considered under multiple American administrations.
Long history
North Korean expertise in tunnelling and underground fortifications has its origins in the Korean War when U.S. forces dropped 635,000 tons of bombs across the peninsula, and in parallel to major investments in developing a modern air defence capability, the construction of key military and industrial sites deep underground was seen as key to preparing for a possible future American air assault. A recent example of North Korea’s ability to build airbases under mountains was provided in February 2023 when Iranian media released images of the country’s Eagle 44 airbase, which is considered highly likely to have been built with extensive North Korean support. Iran’s Fordow uranium enrichment plant is similarly thought to have been built with extensive North Korean assistance and was heavily fortified under a mountain. While footage of examples from within North Korea is more scarce, the Pyongyang Metro was notably built in 1965 as the deepest in the world after the United States began deploying and rapidly expanding an arsenal of several hundred nuclear weapons in South Korea, which peaked at 950 warheads and was largely aimed at North Korea. Three thick metal blast doors at every entrance allow the metro to serve as a citywide bomb shelter in the case of American nuclear strikes, which appears to have been its primary purpose.
North Korea’s network has allowed it to store and manufacture vast arsenals underground, and move them over long distances on wide underground roads, allowing assets ranging from mobile surface-to-air missile batteries to intercontinental range ballistic missiles to briefly surface, launch, and return to safety. While the country has only relatively recently begun to introduce solid-fuelled strategic ballistic missiles, which can be stored full-fuelled, for liquid-fuelled missiles underground tunnels allow missiles to be fuelled in relative safety from enemy strikes before surfacing briefly for launch. The value of this network was highlighted in 2016 when the Obama administration seriously considered launching strikes on North Korea. The Pentagon had informed the president at the time that options for a limited preventative attack were effectively non-existent as the country’s highly mobile nuclear delivery systems were stored deep underground in facilities which could not be located or neutralised. The Pentagon had concluded on this basis that nothing short of a full-scale ground invasion to occupy the country could disarm North Korea. The importance of North Korea’s underground fortifications was previously also reflected in the emphasis it received in Defence Secretary Donald Rumsfeld’s confirmation hearing in January 2001, when he stated at the core of his argument against launching a military assault on the East Asian state: “They have gone underground across that country in a way that few nations have done…They have underground emplacements of enormous numbers of weapons.” He thus referred to the country’s armed forces as “world-class tunnellers.”
The recent war between Israel and Palestinian militias in Gaza has provided an extreme case highlighting that even for forces with relatively negligible capabilities facing a major army, a relatively shallow and basic tunnel network can serve as a tremendous force multiplier. Israel’s struggles against tunnels in Gaza thus can be seen as an indicator of the tremendous difficulties the United States and its allies would face if attempting an invasion of North Korea, with the balance in manpower and firepower being far less favourable to the invaders while tunnel networks are overwhelmingly better fortified and more sophisticated. Footage from the frontlines has also highlighted the utility of tunnels not only to shield all manner of assets but also to redeploy forces behind enemy lines which even Gaza’s relatively shallow networks have proven highly capable of doing, facilitating multiple effective ambushes of Israeli infantry and armour. With North Korean forces preparing for over 70 years for a possible second American-led invasion attempt, following the first launched in September 1950, massive networks of underground fortifications have provided a key contributor to the country’s ability to deter such action. The proliferation of these tunnelling technologies on smaller scales abroad has provided an important demonstration of their potency, and following Israel’s struggles against Hezbollah’s tunnel network in 2006, its invasion of Gaza is expected to only further contribute to dissuading Pyongyang’s adversaries from considering testing its own defences.
The writer’s previous related assessment covering the North Korean proliferation of underground fortifications in southern Lebanon is available here.
Views expressed in this guest column do not necessarily reflect those of Daily NK.
February 14, 2024 at 05:30AM
by DailyNK(North Korean Media)