The 21st century will be a battle on the urban front

If war is hell, as General William Tecumseh Sherman said, then urban warfare is its ninth circle.

Scenes of abject devastation emanating from Mosul in Iraq, and to a lesser extent Marawi in The Philippines, drive home that waging war in built-up areas ­causes huge damage to civilian infrastructure. Not only does this amplify the humanitarian costs of civilian casualties and large-scale population displacement, it potentially undermines the legitimacy of governments trying to reassert control in civil conflicts.

This is not lost on the insurgents, past or present. The paradox of destroying a town to save it, coined at the height of the Vietnam war, remains a confronting reality a half-century on.

The challenges of urban warfare are not new, but the recent seizure of cities by Islamist insurgents in Iraq, and a more diffuse group of fighters in The Philippines, points to a change of tactics, away from traditional terrorist acts and guerilla orthodoxy. However, it would be unwise to inflate the comparison. Islamic State in Iraq and Syria is a far more ­potent threat than the Abu Sayyaf group in the southern Philippines or the Maute group, Abu Sayyaf’s local ally in Marawi and the would-be Islamic State franchise there.

Islamic State had two years to prepare for the defence of Mosul, a city of 1.5 million people. This explains why it took nine months for Iraqi forces to retake the city, house by house, despite wide-ranging support from international coalition ­forces. Marawi is much smaller and has been a different sort of battle, developing from a botched police raid to capture Abu Sayyaf leader Isnilon Hapilon, into an impromptu military siege. The local terrorist alliance around Hapilon and the Maute group remains relatively small and local. Only about 50 foreign jihadis are thought to have infiltrated into Marawi, though their influence was felt disproportionately in the latter stages of the battle through the appearance of improvised explosive devices.

Significantly, the two established insurgent groups in Mindanao, the Moro National Liberation Front and the Moro Islamic Liberation Front oppose Hapilon and the Maute group. Their longstanding objective is increased autonomy from Manila, not the creation of an Islamic State-inspired caliphate.

After nearly three months, the fighting in Marawi is finally winding down. Between 40 and 60 fighters are estimated to be holding out, their ammunition apparently running low. The fact that it has taken the Armed Forces of the Philippines, with non-combat assistance from the US and Australia, this long to retake the town bears out their relative inexperience and lack of specialised equipment for urban warfare.

The insurgents fighting in Mosul and Marawi are different, but the military response in both siege battles offers a closer point of comparison, with its heavy reliance on firepower, particularly airstrikes. The US was recently reported to be mulling lethal drone strikes in the southern Philippines as part of its assistance to the Philippines army, although it appears unlikely The Philippines would ­accept such an offer, given domestic sensitivities towards any US combat role in its former colony. While minimising military casualties, the resulting damage risks turning tactical victory into strategic defeat if it further alienates populations and the government cannot repair infrastructure and quickly restore services.

Guerilla warfare has long been characterised by insurgents operating from the sanctuary of impenetrable jungles or mountain lairs. Groups of fighters survived by seeking to remain beneath the “detection threshold”, a military term used to determine the identified existence of a threat.

Now, Western military forces can target insurgents in remote areas with relative ease and little fear of collateral damage. The US strike on Islamic State fighters in Afghanistan earlier this year using a 10,000kg “mother of all bombs” is an example.

With the growing array of intelligence, surveillance and reconnaissance assets, such as armed remotely piloted aircraft and satellite imagery, it is increasingly hard for insurgents to stay beneath the detection threshold through remoteness alone. By seizing urban areas and forcing civilian populations to stay, as Islamic State did in Mosul, they forgo being undetectable but stay under the discrimination threshold, because of the difficulty in discriminating fighters from the surrounding population. Occupying urban areas not only keeps insurgents beneath the discrim­ination threshold, it also forces the governments they oppose to make hard choices: besiege the urban area, inflicting prolonged hardship on civilians, or storm the city and potentially take heavy casualties.

The urban environment is perfect terrain for the defender. Many Western military advantages are negated. Operations require large numbers of personnel, while armoured vehicles cannot manoeuvre freely. Area weapons such as artillery are less effective. Roads become impassable fire lanes. Doorways are such obvious entry points they are known in the infantry as funnels of death. Sewers allow the enemy to reappear in areas previously cleared. Snipers, machineguns, IEDs, suicide bombers — all can attack from myriad directions. In Mosul, suicide bombers using prepositioned up-armoured cars packed with explosives emerged from underground carparks or garages as the Iraqi forces moved through the city. The time from the threat ­appearing to detonation was usually measured in seconds.

Urban fighting has long been characterised by high numbers of casualties for the attacking force. US forces fighting to retake Hue during the Tet offensive in Vietnam suffered an average daily ­casualty rate (killed and wounded) of 20 per 1000 servicemen, almost three times that suffered during the assault on Okinawa in 1945. During the most intense phase of the battle for Hue, fighting for the Citadel, this leapt to 52 per 1000. The US casualty rate on D-Day at Omaha Beach was about seven per 1000.

The US Department of Defence estimates 40 per cent of the elite Iraqi Counter-Terrorism Service have become casualties in the battle for Mosul. According to Al Jazeera, more than 8000 Iraqi soldiers and policemen had been killed by May, a toll that undoubtedly will have risen in the two months of fierce fighting that followed before Mosul was declared liberated. This is a high cost considering Islamic State’s pre-battle strength was estimated by the Iraqi military at 5000 to 6000 fighters. Marawi was captured by about 500 militants. Two months of combat has resulted in at least 119 government troops killed, although the real number could be higher.

Facing such casualty figures, the US-led coalition in Iraq and the Philippines army increasingly have relied on the combination of surveillance assets and airstrikes to target insurgents. While undoubtedly saving military lives, the collateral cost of such a strategy is staggering. The UN assesses that of western Mosul’s 54 residential districts, 15 are so badly damaged that most houses are uninhabitable and half of the buildings in another 23 districts were destroyed. It probably will take years to rebuild the city and the bill for basic infrastructure alone is likely to top $1 billion.

While the firepower used in Marawi pales in comparison with Mosul, artillery and airstrikes have extensively damaged central districts. In both cities, if the damage is not restored quickly or ­alternative accommodation made available, festering resentment against the respective governments is certain to follow. Upwards of 200,000 remain dis­placed by the fighting in Marawi. The fear is the battle will act as a beacon to attract regional radicals and Islamic State veterans fleeing the battlefields in Iraq and Syria.

Does the increasing lethality available to insurgents and the tactical advantage offered by the urban environment mean that more towns and cities will be targeted by them? Probably.

Will the response need to rely on overwhelming firepower to dislodge them? Not necessarily. In 2013, a disaffected faction from the MNLF captured Zamboanga city in the southern Philippines. The military reaction was rapid. Within three weeks the Philippines army handed the city back to the police, having reportedly killed 183 rebels and captured 292, for the loss of 23 soldiers and policemen. The prompt use of infantry, with combat engineers and light armour in support, denied the rebels time to construct defences.

Herein lies the key to an effective tactical response against the growing threat of urban warfare. Governments need to have a rapidly deployable combined arms force, trained in urban warfare that can respond quickly at the first appearance of militants in towns or cities.

Time is critical; the longer insurgents have to prepare defences, the harder it will be to dislodge them. Providing this training around the world will enhance significantly the resilience of countries at risk from terrorism.

Australia has a regional role to play. The successes of Australian training teams in Taji, Iraq, are well publicised. Less well known is the work carried out by Australian mobile training teams helping the Papua New Guinea Defence Force as part of Canberra’s defence co-operation program.

These training teams are drawn from infantry, engineers and logistics personnel, and provide tailored short-term training packages that target specific areas for improvement within the PNG army. They also improve interpersonal connections between the two defence forces, as well as exposing Australian personnel to an environment to which they may have to deploy in future, whether providing humanitarian aid following a natural disaster or for a stabilisation operation.

The use of small training teams in “upstream engagement” is becoming more widespread among Western militaries. Britain’s international defence engagement strategy highlights the benefits of short-term training teams: 24 detachments provided training to 15 countries in 2014. The US has a similar concept of building host nation capacity through embedded training teams.

The mobile training teams provide a model that Australia could adapt to deliver urban warfare training to other regional partners such as The Philippines, so that regular forces are better able to react rapidly to insurgent uprisings in towns and cities.

This low-cost, low-risk training model should focus on enabling host nation forces to improve the professionalism and capacity of their infantry, combat engineers and armoured vehicle crews in urban warfare. This will empower governments in the region to prevent Islamic State gaining an urb­an foothold without having to rely heavily on air power or artillery.

However, in areas of existing conflict such as the southern Philippines, efforts to build tactical resilience to respond to urban sieges are likely to succeed only as part of an overall political settlement with non-jihadist insurgent groups.