PARIS/MOSCOW: The United States Tuesday made its strongest indication yet that the battle to retake the Syrian city of Raqqa from Daesh (ISIS) could be fast approaching, saying it would “overlap” with an already unfolding assault in Iraq to seize the city of Mosul.

Defense Secretary Ash Carter, speaking to reporters after meeting allies in Paris, did not disclose the timing of the Raqqa campaign but said preparations were on track.

“Yes, there will be overlap [in the Mosul and Raqqa campaigns] and that’s part of our plan and we are prepared for that,” Carter said after a gathering of 13 countries in the U.S.-led coalition fighting Daesh.

His French counterpart, Defense Minister Jean-Yves Le Drian, also said preparations were on schedule.

Mosul, a city of 1.5 million people, and the smaller Syrian city of Raqqa are the two pillars Daesh’s self-declared caliphate, and recapturing them would be a pivotal defeat for the militants.

U.S. officials acknowledge the Mosul campaign could take weeks or months, giving military planners time if they want both campaigns to run concurrently at some point.

A senior U.S. military official, speaking to reporters traveling with Carter, suggested the Raqqa kickoff would likely follow some additional successes in Mosul. He also said military planners would seek to avoid overstretching U.S.-led coalition assistance, which includes airstrikes.

“I think everything is trending positively, [and] that we should be able to commence that effort sometime in the near future,” the official said.

Arab forces are expected to be the ones to take the city itself, U.S. officials say.

French President Francois Hollande, addressing the meeting, said the offensive on Mosul could trigger an outflow of foreign fighters – a concern for European nations wary of attacks by Daesh militants returning from Iraq and Syria.

Carter said more than 35 Daesh commanders were targeted by the coalition in the past 90 days.

The U.S. military official who briefed reporters with Carter said most of Daesh’s external plots are still likely being hatched from Raqqa, as opposed to Mosul.

Hollande warned that the coalition needed to watch out for flows of Daesh fighters from one besieged city to another.

On the Aleppo front, meanwhile, Russia said Tuesday it would extend a moratorium on airstrikes on the city into a ninth day, without specifying for how long.

Defense Ministry spokesman Maj. Gen. Igor Konashenkov said Russian and Syrian planes had not even approached, let alone bombed, the devastated city since last Tuesday when Russia suspended airstrikes ahead of a pause in hostilities.

Sergei Rudskoi, a Defense Ministry official, said that meant Russian and Syrian planes would continue to stay out of a 10-km zone around Aleppo.

The Syrian Observatory for Human Rights, however, said airstrikes had resumed since the lull in fighting ended Saturday, focusing on major front lines, including in the city’s southwest. There had been no civilian deaths from airstrikes inside eastern Aleppo, however, the group said.Ibrahim Abu al-Laith, a civil defense official in eastern Aleppo, also said airstrikes and shelling had hit the rebel-held half of the city near front lines in the past week.

Rudskoi said around 50 women and children had managed to leave Aleppo late Monday despite the dangers and were escorted by Russian military officers. He said Russia was ready to help broker further cease-fires to allow wounded civilians to be evacuated.

Elsewhere, Turkish-backed rebel forces in northern Syria have gained control of three areas – Tuways, Al-Gharz and Tlatinah south of Akhtarin – in the last 24 hours as they press a 2-month-old operation to drive Daesh and Kurdish militias from the border, the Turkish army said. The assault appeared to mark the first advance in days, widening their territory since the start of the operation to 1,280 square km, according to the statement.