Unfolding events in the Basra-Umm Qasar region represent a microcosm of the sort of conflict that the Iraq war has fast become. Recent news footage showing British troops searching civilians and cars at a checkpoint near Basra could almost have been shot in Northern Ireland had it not been for the appearance of the locals and their surroundings. Similarly, the pitched tank battle fought by the elements of the 7th Armoured Brigade hours earlier brought to mind encounters faced by their regimental predecessors in North Africa over 60 years ago. Elsewhere, in southern Iraq, other British troops sought to deliver humanitarian aid amid ugly scenes reminiscent of the gray-area peace operations that erupted in the wake of the Cold War. 

Viewed together, such vignettes present a picture of the type of conflict that Gen. Charles Krulak - U.S. Marine Corps Commandant between 1995-1999 - once termed a "three-block war." In such a scenario, troops find themselves engaged in a spectrum of operations, from humanitarian missions, through peace keeping and peace enforcement-type actions, to full-blown combat - sometimes within the space of three city blocks. 
The success of such operations will rest largely with the "strategic corporal" (another "Krulak-ism" as the prescient observations of their former chief are sometimes referred to in Marine Corps circles) - the junior leaders whose actions and orders have, partly due to the exponential growth of the mass media, significantly increased in their geo-political influence. 

An appreciation that the behavior and decisions of even the most junior leaders and soldiers can percolate up to affect national policy was demonstrated in an incident in the early days of the Iraq war during fighting around Basra. On that occasion, understandably zealous U.S. Marines raised their regimental and national colors to mark some territory they had just fought hard to take. Military and national pride (and, not insignificantly, unit morale) notwithstanding, these colors were quickly removed lest they inadvertently portrayed the coalition action in Iraq as a war of occupation rather than liberation. That the potential implications of the Marines' action were immediately realized and the flags quickly lowered bodes well. In what is effectively the most politically constrained large-scale conflict of modern times, this will not be the last such sensitive incident.

Basra has also seen the various elements of the three-block war played out in and around urban areas - long-viewed by many in the U.S. military as the most likely environment for future conflicts. Military Operations in Urban Terrain (MOUT) have also occurred elsewhere in southern Iraq, with U.S. troops involved in such combat at various crossing points on the Euphrates. The cities astride these crossing points may yet have to be captured rather than contained if American supply lines are to be freed up and if locals are to be convinced of the coalition's resolve and ability to depose Sadaam Hussein's regime. At the moment, the final showdown looks likely to occur on the streets of Baghdad, raising the specter of more intense urban fighting than has been experienced thus far. The battle of Baghdad, should it transpire, will see coalition troops forced to navigate an "urban triad" of interconnected factors related to the city's physical terrain, civilian population, and infrastructure.

The physical terrain fought over in an urban combat is peculiarly multi-dimensional, and comprises planes that each present their own difficulties to military forces. For instance, in the airspace above a city, the irregularities of natural terrain are compounded by man-made structures of varying height and density. This makes air operations much more challenging with aircraft often forced down "urban canyons" and exposed to ground fire from the various surface areas below. This happened in Mogadishu, when the initial downing of an American helicopter led to heavy fighting on the ground when the subsequent rescue mission went awry. The surface areas of cities, which encapsulate any natural terrain as well as streets and roads, are themselves broken up by super-surface comprised of the various floors and roofs of building and other man-made structures as well as subsurface formed by underground transportation systems, and maintenance and utility tunnels. All these areas represent ideal defensive positions.

The high population density of urban areas further complicates efforts to capture and clear them by armed action, making it all too easy for civilians to be killed and injured in such operations. Size and density are not the only aspects of a city's population to be considered. Socio-cultural factors such religious and political affiliations also play a role, as do clan, tribal, economic, and class divisions. Knowledge and understanding of such factors were crucial throughout the British Army's long involvement in military operations in Belfast and other urban centers in Northern Ireland, as it will be in Iraq.

Considerations related to a city's infrastructure are also pivotal in the planning and execution of urban operations. Such infrastructure can vary from the relatively simple (as in Afghanistan) to the relatively complex (such as in Baghdad and elsewhere in Iraq). The physical infrastructure comprised of energy and transportation system is paralleled by a service infrastructure including medical, emergency, and government services. That these services often have dual military and civilian uses further complicates the decision over whether to target them. This was shown by the somewhat belated attacks on Baghdad's television station. The importance of infrastructure was also evidenced by the ongoing humanitarian crisis in Basra, partly caused by a breakdown of the city's water infrastructure, which has apparently motivated the British decision to reduce the city in an attempt to limit further civilian suffering.

As such factors demonstrate, MOUT is never easy. Some of the more reprehensible practices of Iraq's military will further complicate it. Human shields, suicide bombings, faked surrenders, and military forces operating in civilian clothes will make any battle for Baghdad an even bloodier affair. The risk that the Iraqi regime will employ WMD makes such a scenario more nightmarish.

Information will play a key role in helping coalition troops and Iraqi civilians survive this nightmare. The intelligence reports that led to the decapitation attack on the Iraqi regime that opened the overt war indicate that efforts to ascertain the situation within the Iraqi capital have been ongoing for some time. In addition, America had also had months - indeed years - to study Baghdad's physical terrain, population and infrastructure. This, together with the experience and training in MOUT that coalition troops will bring to the task at hand means urban warfare should be less of a force leveler than would otherwise be the case. Militarily, allied troops will prevail. Indeed, in a sense the political battle for Baghdad will be more difficult. This battle has already begun and will heighten when the first pictures of coalition and civilian casualties sustained in street fighting in Baghdad are broadcast. It is a battle that also must be won if the lives lost taking the Iraqi capital are not done so in vain.

Mark Burgess is a military analyst with the Center for Defense Information, an independent think tank in Washington, D.C.