This is nothing, wait until they try and take Mosul.

(Reuters) – Iraq has delayed its assault on the city of Falluja because of fears for the safety of civilians, Prime Minister Haider al-Abadi said on Wednesday, as his forces halted at the city’s edge in the face of ferocious resistance from Islamic State fighters.

Abadi’s decision to halt, two days after elite Iraqi troops poured into the city’s rural southern outskirts, postpones what was expected to be one of the biggest battles ever fought against Islamic State.

The government, backed by world powers including the United States and Iran, has vowed to win back the first major Iraqi city that fell to the group in 2014.

“It would have been possible to end the battle quickly if protecting civilians wasn’t among our priorities,” Abadi told military commanders at the operations room near the frontline in footage broadcast on state television. “Thank God, our units are at the outskirts of Falluja and victory is within reach.”

Abadi first announced plans to assault Falluja 10 days ago. But with 50,000 civilians still believed trapped inside the city, the United Nations has warned that militants are holding hundreds of families in the center as human shields.

After heavy resistance from Islamic State fighters, the troops have not moved over the past 48 hours, keeping their positions in Falluja’s mainly rural southern suburb of Naimiya, according to a Reuters TV crew reporting from the area.

Abadi’s initial decision to assault Falluja appears to have gone against the plans of his U.S. allies, who would prefer the government concentrate on Mosul, rather than risk getting bogged down in a potentially drawn out fight for a smaller, potentially hostile Sunni Muslim stronghold like Falluja.