MOSUL/BAGHDAD: Islamic State fighters defended their remaining stronghold in the Old City of Mosul on Monday, moving stealthily along narrow back alleys as US-backed Iraqi forces slowly advanced. The intensity of fighting was lower than on Sunday, when Iraqi forces announced the start of the assault on the Old City, a Reuters visuals team reported from near the frontlines. The historic district, and a tiny area to its north, are the only parts of the city still under the militants’ control. Mosul used to be the Iraqi capital of the group, also known as ISIS. The International Committee of the Red Cross (ICRC) expressed alarm on Monday at the situation of the civilians in the Old City, estimated at more than 100,000 by the United Nations.