"The worst policy is to attack cities ... attack cities only when there is no alternative." wrote Sun Tzu in his Art of War (c. 500 BC). He was correct: urban fighting involves challenges and costs that can far exceed those of conventional warfare. The effectiveness of superior weapons and communications technology is blunted in the urban environment, but new tactics, training and equipment are being developed to try to overcome these disadvantages.
Armies fight in cities not because they want to, but because they have to. Population, especially in the developing world, is rising rapidly and becoming more city-centric. One estimate suggests that by the year 2010 75 percent of the world's population will live in urban areas. American military doctrine recognises that cities are the battlefields of the future, but urban warfare presents special challenges, especially for the attacker.
The problems are greatest for technologically advanced attackers who face determined defenders. Classic recent and current examples are the Russians in Grozny, Israelis in the towns of the Gaza Strip and West Bank and American forces in Iraq and Afghanistan. Urban fighting sharply reduces the effectiveness of sophisticated sensors and weaponry and favours less sophisticated mobile weaponry, local knowledge and guerrilla tactics.
Cities have two defining features that make urban warfare difficult: buildings and people.
Imagine a battlefield that has been folded back on itself multiple times, so that a conflict which would cover a much wider area on level ground is compressed into a few square kilometres. This is the urban battlefield, vertical rather than horizontal, a '360-degree fight' in which upper floors of buildings, basements, sewers and tunnels are all places where defenders can hide from and fire on attackers in the streets.
This compressed and complex battlefield makes it difficult for commanders and troops to gain an overview of the action, while the small area of action increases the likelihood of fratricide. The urban landscape offers increased possibilities for ambushes and flanking operations: buildings, and even the rubble from buildings, provide cover for snipers and mobile artillery such as RPGs (rocket-propelled grenade launchers).
Also, a tank that breaks down can block an entire line of advance, a fact that the Chechen defenders used to their advantage in the 1994-95 battle for Grozny. Confident in their superior firepower, the Russians paraded through the streets in columns converging on the presidential palace. By disabling the tanks at the front and rear of each column, the Chechens immobilised the rest and were able to attack them at leisure.
Conventional air strikes are of limited effectiveness in cities, partly because of the greater risks of collateral damage and partly because of terrain features. Urban canyons reduce the ability of aircraft to manoeuvre, and so make them more vulnerable to attack by air defence artillery and missiles hidden on high buildings. The combination of high-rise buildings and low cloud further reduces the effective above ground level (AGL) operating area, while aircraft silhouetted against overcast skies are easy targets. The 'clutter' of lights, smoke and dust can obscure ground fire or missile launches and create visual confusion.
Tanks, artillery and missile batteries are at a similar disadvantage, designed for firing at targets at a distance and on the flat. Closely packed buildings deny conventional weapons adequate range and lines of sight, while limits on gun elevation and depression create areas that are safe from fire--for instance in basements and in tall buildings.
Other disadvantages are subtler. Night vision goggles and thermal sights may be dazzled by city lights, fires and background illumination. Reduction in visibility can similarly degrade the performance of weapons sensors and laser- or optically-guided weapons. Turbulence caused by wind channelled along city streets can affect aircraft performance and weapons delivery. Smooth urban surfaces increase the chance of ordnance ricocheting or 'rabbiting', while impact-fused explosive rounds may not detonate at all if fired against rubble. Fighting in close quarters means that fragments from the exploding target as well as muzzle blast and back blast can cause injury to those firing the weapon.
Navigation and communication capabilities are also fragmented by the city landscape. High buildings block radio communication and GPS satellite navigation. Available military maps are often inadequate and out-of-date, especially once landmark buildings are reduced to piles of rubble. Important battle areas below ground and inside buildings are not visible to reconnaissance planes or drones, and stealthy movement is difficult in a strange environment.
People--the attackers, defenders, civilian population and other groups such as the media--further complicate the urban warfare picture. One problem the urban commander faces is situational awareness, or knowing where all these people are. With communication links faulty and reporting difficult, basic questions such as; Where am I? Where are my soldiers? Where are friendlies? Where is the enemy? may be difficult to answer with any certainty.
The small combat units that are typical of urban warfare are even more isolated, physically and in terms of communications, both from their commander and from other units in the same area. Fighting at close quarters is stressful and increases the chances of fratricide and breakdowns in discipline.
In urban warfare, the defenders can be difficult to distinguish from the civilian population, while relations with the city's inhabitants can be as complex as the terrain. General Charles Krulak, the former Commandant of the United States Marine Corps, described future urban operations as a 'three block war', suggesting that the attackers may be providing humanitarian assistance in one part of the city, conducting peacekeeping operations in another and fighting a lethal mid-intensity battle in a third part.
There is a fourth 'block': the media. By denying access to foreign journalists, the Israeli Defence Force left the Palestinians to tell the only available stories of the April 2002 attack on Jenin in occupied territories of the West Bank, and widespread media reports of a massacre resulted. In January 2003, a conference report by the Jaffee Centre for Strategic Studies at Tel Aviv University concluded that greater openness would be essential in future Israeli combat operations. But media access creates its own problems. Ever since the battle for the city of Hue during the Vietnam War, commanders have had to reckon with the impact of their operations on home viewers watching the evening news.
US Army doctrine recognises the urban warfare threat to non-combatants and recommends removing them from the scene. But this can be easier said than done. The Israeli forces attempted to evacuate Jenin before beginning action against Palestinian Islamic Jihad forces there, but approximately 2000 of the 13,000 inhabitants of the camp chose to stay behind. In the days before the November 2004 assault on Fallujah, the offer of free passage to non-combatants allowed hundreds of insurgents, including their leader Abu Musab Zarqawi, to escape.
The Cost Factor
Urban warfare requires more of almost everything than conventional warfare does, and casualties are historically higher. In 2003 US Army doctrine assumed three to six times greater casualty rates than in any other environment, although in recent engagements such as Fallujah the initial toll was lighter than expected.
Casualties come not just from weapons but also from shattered glass, falling debris, rubble, ricochets, fires and falls from heights. Stress, illness and environmental hazards such as contaminated water and toxic industrial materials increase the numbers. Even without casualties, more troops are needed to attack a city than to defend it. A proportion of these will need to stay back to secure captured buildings and keep access routes clear, reducing the numbers available for the advance.
In the wake of the Grozny campaign, some analysts, both Western and Russian, argued that the costs of urban warfare were too high and recommended standoff tactics, in effect a modern siege instead. But most accept that fighting in cities is a necessary evil. If this is so, what are the factors that can help make urban warfare more effective?
What is profoundly different about urban warfare is the terrain. Thinking, tactics, training and technology all need to adapt to a very different situation.
Until recently military thinking was dominated by the 'total war' model of World War II, in which civilian deaths and the destruction caused by heavy bombing were acceptable. One of the differences in modern urban warfare is that avoiding collateral damage has become a major declared objective. This radically changes military rules of engagement.
Serious military thinking about the problems of modern urban warfare is relatively new. The 1976 edition of US Army field manual FM 100-5, Operations, admitted, > This is changing, and the result is tactical thinking which takes into account the special circumstances of three-dimensional warfare.
Two important areas of tactical thinking concern the roles of tanks and aircraft, especially attack helicopters, in modern urban warfare. The lessons of Grozny and the 'BlackHawk Down' scenes in Mogadishu suggest that both platforms are vulnerable in urban operations, but their advocates say that a change in tactics, in particular their use in combined operations, can make both an effective tool.
A 2001 monograph by Major Frank Tate of the School of Advanced Military Studies, United States Army Command and General Staff College, Fort Leavenworth, Kansas, argues that 'attack helicopters have the flexibility, precision...