The battle to retake Mosul, Iraq's largest jihadist hub, could take up to a year to plan, US President Barack Obama's envoy for the coalition against the Islamic State group said Friday.
"I would see that Mosul will probably go as an operation within a year... The operation will kick off within a year," John Allen told reporters in Baghdad.
The northwestern city is Iraq's second largest. The IS seized it on June 10 and it has since used it as a headquarters and a base from which to launch further offensives.
"It is a battle that is going to obviously demand as much planning and preparation as it possibly can," said Allen, who met Prime Minister Haidar al-Abadi on Thursday.
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Mosul "was the place where Abu Bakr al-Baghdadi exposed himself, the place where the difficulties of the ISF (Iraqi security forces) really began to cascade," he said.
Baghdadi, the self-proclaimed caliph of the so-called Islamic State his group declared over parts of Iraq and Syria, made a rare appearance at Mosul's mosque in early July.
The federal army collapsed when jihadists thrust into Mosul in early June, abandoning a huge arsenal of US-made vehicles and weaponry that turned IS into an even more formidable foe.
Allen said it would take time to restructure the army and make it a force capable of winning the war against IS.
He praised Abadi's plan to build a National Guard that could incorporate Sunni tribal forces at the provincial level and assist the federal army.