Hard and Deeply Buried Targets (HDBTs) around the world

With the necessary technology becoming ever more widely available, a large number of Washington’s potential military adversaries have been able to develop underground facilities in recent years. U.S. military planners have expressed particular concern that these governments may use these facilities to manufacture and store weapons of mass destruction (WMD). Buried deep underground, these stores, along with command and control centres for them, could remain beyond the reach of U.S. weaponry. The U.S. government’s perception of the threat posed by these facilities has been spurred by the activities of a number of countries it views as hostile.
Iraq

At the outset of the Persian Gulf War the United States quickly realized it would need improved conventional capabilities to deal with Saddam Hussein’s network of underground facilities. The 4,000-pound GBU-28 bunker buster (a conventional bomb) was put together in record time to support targeting of the Iraqi hardened command bunker by adapting existing material. The weapon was not even in the early stages of research when Kuwait was invaded but was produced quickly enough to be deployed in combat. Only two of these weapons were dropped in Desert Storm, both by F-111Fs, with one weapon successfully destroying its target.

The United States realized the value of such weapons and invested heavily in their development, going on to produce the GBU-37, an improved version of the GBU-28. But the Pentagon also feared that future adversaries would seek to develop improved underground bunkers to evade U.S. attack. As the Defence Department’s report to congress on the outcome of the war stated, “Future adversaries may be expected to invest in protective shelters and bunkers for aircraft and [command and control] facilities.”

Libya
From the mid-1990s onward, U.S. intelligence reports became increasingly concerned about the development of a suspected chemical weapons facility near the town of Tarhunah, 65 kilometres (41 miles) southeast of Tripoli. The facility is a set of underground tunnels built into the side of a mountain with a thick layer of concrete protecting the tunnels. Amid growing tension over the issue between the United States and Libya, Egyptian President Hosni Mubarak sent investigators to visit Turhunah in May 1996. The investigators saw the tunnels, but reported no evidence of chemical weapons production.

Amid growing international pressure, U.S. intelligence agencies reported in early 1997 that Libya had halted construction work at the facility. However, late in the year Israeli intelligence claimed that work at Tarhunah had resumed and U.S. intelligence reports continue to express concern about the facility. In 1997, additional reports emerged that Libya was constructing a 3,200-kilometre (2,000-mile) long network of underground pipes with passageways sufficiently large to move military troops and equipment. The reports alleged that the pipes intersect with the underground facility in Tarhunah.

North Korea
Reports have regularly emerged of underground military developments in North Korea. Certain reports claim that Pyongyang has built an extensive network of underground tunnels complete with storage facilities and routes, suitable for use in a military invasion of South Korea. More specifically, in August 1998 the New York Times reported that North Korea was constructing an underground nuclear reactor. U.S. intelligence sources claimed that 15,000 North Koreans were working on the facility at Kumchang-ri, 40 kilometres (25 miles) north of the nuclear research facility at Yongbyon.

In March, 1999 U.S. inspectors were given permission to visit the facility and reported that while they found no evidence linking it to North Korea’s nuclear program, they remained unclear as to its true purpose. In spite of this, U.S. officials continue to express concern about the strategic implications of Pyongyang’s excavations. In 2000, Franklin Kramer, assistant secretary of defence for international security, told the Senate Foreign Relations Committee that North Korea has “a great number of underground facilities they continue to develop.”

Yugoslavia
Operation Allied Force, the 1999 air campaign over Serbia and Kosovo, is seen by some as demonstrating the U.S. military’s inability to destroy underground targets. In a September 2001 interview, Paul Robinson, the director the Sandia nuclear weapons laboratory in New Mexico, stated that the use of conventional weapons against Serbian bunkers had “very little effect” because it “takes far too many sorties and conventional weapons to give you any confidence that you can take out underground bunkers.” The conflict is also cited in the Defense Department’s “Report to Congress on the Defeat of Hardened and Deeply Buried Targets” from October 2001:
“The Persian Gulf War and the series of conflicts in the Balkans revealed that facility protection, by hardening, concealment, and defenses, remains an effective response to the technology advantages in intelligence and weaponry enjoyed by the United States and its allies.”

However, this assessment is not supported by the Defence Department’s report from immediately after the conflict. In January 2000, Assistant Defense Secretary William Cohen reported that conventional allied munitions had successfully destroyed all the underground facilities they targeted. Citing a reconnaissance visit to Kosovo carried out shortly after the visit, Cohen reported that, “At every bunker site visited, the team found that NATO attacks were successful.” Other analysts argue that the failing of NATO’s bombing campaign had less to do with Serbia’s use of underground facilities than the mobility of Belgrade’s forces, poor allied intelligence and a refusal to fly sorties below 4,500 metres (15,000 feet).

Afghanistan
Concerns about opponents’ use of underground facilities again came to the fore during the ongoing military campaign against Al Qaeda and Taliban forces in Afghanistan. U.S. defence officials estimate that there are hundreds, if not thousands of caves, tunnels, aqueducts and bunkers in the mountains and deserts of Afghanistan, the legacy of centuries of warfare and of an ancient farming technique that relies on underground water supplies. Found primarily in eastern and southern Afghanistan, the hideouts include natural limestone caverns and tunnels, and man-made passageways.

To tackle the Afghan facilities the Pentagon developed two new weapon systems, including a thermobaric weapon designed to fill tunnels with fireballs. The Defense Threat Reduction Agency was tasked with producing the weapon, and the first of the BLU-118 warheads was used in Afghanistan in January 2002.

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