Sprawled on the boarded-up balcony of a two-story house, the barrel of his rifle poked into a hole cut in the wood, the Philippine army sniper calls for quiet before taking his shot. "Firing," he says evenly, before the .50 caliber shot rings out, sending tremors through the house. He was firing at a home less than a kilometer (a half mile) away, believed to be a stronghold of militants who have been holed up in Marawi City for over five weeks. A spotter sat next to him, with his scope set into another hole. The two spoke quietly to each other as the sniper took three more shots across the Agus river into the militant-held commercial district of Marawi, now a battleground strewn with debris from ruined buildings. Scores of bodies are rotting in the area, and the stench mixes with the smell of gunpowder. Thousands of soldiers are battling to retake the southern Philippine city, where militants loyal to Daesh (the so-called IS) launched a lightning strike on May 23. The southern Philippines has been marred for decades by insurgency and banditry. But the intensity of the battle in Marawi and the presence of foreign fighters from Indonesia, Malaysia, Yemen and Chechnya fighting alongside local militants has raised concerns that the region may be becoming a Southeast Asian hub for Daesh as it loses ground in Iraq and Syria. As troops poured in to contain the siege, few were expecting a slow, difficult and unfamiliar urban war. "We are used to insurgencies...but a deployment of this magnitude, this kind of conflict is a challenge for our troops," said Lt Col Christopher Tampus, one of the officers commanding ground operations in Marawi. He said progress in clearing the city has been hindered by militant fire and booby traps like gas tanks rigged with grenades. After weeks of military airstrikes and shelling, Marawi, a lakeside city of around 200,000 is now a ghost town, the center of which has been reduced to charred rubble and hollow structures. Buildings in the military-controlled areas of the city are still standing but deserted after residents fled. Authorities estimate around 100 to 120 fighters, some of them as young as 16 years, remain holed up in the commercial district of the city, down from around 500 at the beginning of the siege. The fighters are holding around 100 hostages, according to the military. Military aircraft drop bombs on the militant zone almost every day. From the outskirts of the city, mortar teams take aim at what they call "ground zero," the heart of the conflict. "Mortars are designed to target people and smaller areas than the airstrikes." said mortar specialist Sgt. Jeffery Baybayan, as he jotted down coordinates that come crackling over a radio from an observer closer to the conflict area. "Hitting targets accurately can be difficult and we're expending rounds without hitting targets. We are concerned about our own troops that are very close to the enemy area," he added, as the mortars exploded in the city, sending up plumes of thick black smoke. — Reuters