As the "Islamic State" militant group faces expulsion from Mosul, a retreat to Raqqa could be in jeopardy. Campaigns against the two cities are likely to overlap, US officials said.
The siege against Mosul will likely overlap with a campaign against Raqqa, US Defense Secretary Ash Carter said on Tuesday, signaling that a push to isolate the group's Syrian bastion may not be very far off.
"Yes, there will be overlap and that's part of our plan and we are prepared for that," Carter told a news conference at a Paris meeting of defense chiefs.
French President Francois Hollande warned IS fighters could flow out of Mosul to Raqqa and potentially onwards to Europe, as he called for greater intelligence sharing.
"In these columns of people leaving Mosul will be hiding terrorists who will try to go further, to Raqqa in particular," Hollande said.
"Daesh must be eliminated everywhere. Any stronghold represents a threat," he added, referring to the group by its Arabic acronym.
European leaders have expressed worries that the battle to retake Raqqa had not yet begun.
Speaking in Cyprus, France's Foreign Minister Jean-Marc Ayrault called for the US-led coalition to turn its attention to Raqqa, from where attacks in the Middle East and Europe are planned.
"It's a difficult fight, but we will win," Ayrault said. "We must definitely win the fight everywhere."
Colonel John Dorrian, a spokesman for the coalition, said its air power was preventing major movements of IS fighters between Mosul and Syria.
There was some movement in both directions, he told the DPA news agency, but he also said: "We don't see the type of movement that was seen in the past with large convoys."
Forces within striking distance
Iraqi forces were in the second week of a siege against IS militants in Mosul on Tuesday.
"On our front, we have advanced to within five or six kilometers (three to four miles) of Mosul," Iraq's General Abdelghani al-Assadi told AFP news agency.
"We must now coordinate with forces on other fronts to launch a coordinated" attack on Mosul, he said, speaking from the Christian town of Bartella.
The UN reported that IS fighters have executed groups of civilians in various massacres as Iraqi forces approached Mosul.
No different to Aleppo: Russia
Russia's Foreign Minister Sergei Lavrov said on Tuesday that efforts to recapture Mosul were no different to the Russian backing of a Syrian government offensive to seize rebel-held eastern Aleppo.
"They are preparing an operation to liberate Mosul from terrorists," Russian news agencies quoted Lavrov as saying.
"And in Aleppo, the city needs to be freed from terrorists. With the exact same plea as we made in Aleppo, the American coalition is appealing to residents in Mosul, calling on them to leave. Just like in Aleppo, humanitarian corridors have been set up.
aw/rc (AFP, Reuters, AP, dpa)