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The pending offensive to wrest Raqqa from the control of ISIS will be a deliberate and multi-pronged effort that will draw on the collective efforts of coalition partners, military officials told NBC News on Friday.

The first phase: isolate Raqqa.

"While that isolation is underway, we will continue to plan for the subsequent phases with our partners, including Turkey," the Department of Defense told NBC News in a statement. "We are clear-eyed about the challenges that this complex environment creates, but the need to isolate Raqqa quickly demands the coalition act soon. We will continue conducting precision strikes to reduce the enemy's freedom of movement, attack their leaders and command and control, and their ability to operate."

The offensive to oust ISIS from its capital will get underway within weeks, Defense Secretary Ash Carter told NBC News in an exclusive interview in Paris on Wednesday.

"It starts in the next few weeks," he said, referring to the timeline for an assault led by Arab and Kurdish fighters on ISIS’ Syrian stronghold of Raqqa. "That has long been our plan and we will be capable of resourcing both."

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Carter added: "It’s been long a part of our plan that the Mosul operation would kick off when it did. This was a plan that goes back many months now and that Raqqa would follow soon behind."

Raqqa is the de facto capital of the extremists' so-called caliphate which stretches from Syria into Iraq.

Carter just returned from Iraq, where some 5,000 U.S. personnel are supporting the massive military campaign to retake Mosul from ISIS that began on Oct. 16.

When asked whether U.S. special forces or other troops would be sent inside Mosul or Raqqa to gather intelligence or hunt "high-value combatants," Carter replied: "They are not near [Mosul] at this time ... Our forces do accompany .... the Iraqi security forces and the Peshmerga. So they will get nearer to the city as those forces get nearer to the city ... We are not going to be part of the occupation or hold forces."

Carter spoke to NBC News on Wednesday in Paris, where he has been meeting with his counterparts from other Western countries.

Some European leaders have said they were concerned the effort to take Raqqa had not begun yet, which would allow the extremists to continue planning and inspiring the type of attacks that have hit France and Belgium during the last year.

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Carter also told NBC News that he was "outraged" by revelations the Pentagon was forcing thousands of soldiers to return bonuses given out more than a decade ago to get them to reenlist for six years and fight in Iraq and Afghanistan.

"We need do justice. And we need to do it fast," said Carter, who was heading to a meeting with NATO defense chiefs in Brussels later on Wednesday.

The Mosul battle is expected to take months and follows successful campaigns this year to retake the main cities in Iraq's western Anbar province.

Iraqi security forces and the Kurdish militia have faced ISIS suicide attacks, car bombs and other attacks in their march toward Iraq's second-largest city which the extremists captured in 2014.

ISIS is expected to give ground gradually on the outskirts of Mosul but then stiffen their resistance as the fighting moves closer to the center of the city.