NATIONAL HARBOR, Md. – Iraqi security forces will be ready to retake the city of Mosul by early October, America's top general asserted Wednesday.

Gen. Joe Dunford, Chairman of the Joint Chiefs of Staff, told an audience at the Air Force Association conference here that the Pentagon is now confident that the operation can begin next month.

"We assessed today the Iraqis will have, in early October, all the forces marshaled, trained, fielded and equipped that are necessary for operations in Mosul," Dunford said.

However, the actual launch of the operation may not come immediately, with Dunford noting that the decision "is really just a function of the political decision of Prime Minister [Haider al-Abadi] and we will be in position to provide whatever support, whatever reinforcement those forces need in order to be successful."

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The mission to retake Mosul, the last major urban center controlled by the Islamic State group, has been long brewing, with Pentagon officials indicating it could begin as far back as last December.

Dunford praised the work of forces in Syria operating against ISIL, noting that there are now 30,000 Syrian Democratic Forces, with 14,000 Arabs among them, fighting on the ground.

"Last year at this time we probably had a few hundred vetted Syrian opposition forces on the ground we were supporting, so there has been significant growth," Dunford said. And the Pentagon is "trying to grow more, even as we balance Turkish concerns for our support."

While not directly addressing reports that Russian planes bombed a UN aid convoy this week, Dunford hinted at it, noting "recent events have complicated the situation, and I suspect many in this room, the [Air Force] chief included, will be working hard at that in the coming days."