Eight months after Islamic State fighters captured Mosul in a stunning four-day assault, an Iraqi force and its American allies are going to try and take it back. An official from U.S. Central Command announced on Thursday that a combined Iraqi and Kurdish army of around 25,000 soldiers will launch an offensive in the city in April or May, timed to occur before the arrival of Ramadan and blistering summer weather.

Almost immediately, the announcement has elicited controversy. On Capitol Hill, Senators John McCain and Lindsey Graham sent President Obama a letter accusing the announcement of "risking the success of our mission"—even though such disclosures are not actually that unusual. The news was no more welcome in Iraq, where Defense Minister Khaled al-Obeidi fumed on Sunday that any assault on Mosul was for Baghdad to decide, not Washington.

Nevertheless, the controversy surrounding Thursday's announcement has obscured a far more important question: Is the operation going to work?

On paper, the Iraqi forces should win easily. No more than an estimated 2,000 ISIS fighters currently control Mosul, a city of 1 million. And in addition to their numerical superiority, the Iraqi-Kurdish forces will have additional support of U.S. airstrikes.

But conventional advantages only go so far. Last year, ISIS fighters had little difficulty dispatching the much larger, well-trained, and better-equipped Iraqi forces, many of whom shed their uniforms and fled the city. The problem flows from the country's sectarian divisions. The Iraqi military draws heavily from the Shia majority likely to struggle to control Mosul's now entirely Sunni population.

“It’s all about the composition of this force. 25,000 Iraqi soldiers, where are they going to come from? Are any Shiite militiamen going to be involved?” Aymenn Jawad Al-Tamimi, a researcher at the Philadelphia-based Middle East Forum, told The National.

For the United States, recapturing Mosul is just one part of the country's broader campaign against the Islamic State, which controls large swathes of territory across Iraq and Syria and has made inroads elsewhere. Contrary to perceptions that the group is growing more powerful, American officials have argued that ISIS is now stretched thin—a point echoed by the official who telegraphed the spring assault.

"Militarily, ISIL is in decline,” said the official, using an alternate acronym to describe the Islamic State.

Considering that the group recently established a presence in far-flung Libya, the official's remarks uncomfortably echo President Obama's infamous dismissal of ISIS as a "jayvee team." However, anti-ISIS forces have won important victories lately. Last month, Kurdish fighters drove ISIS out of Kobani, a strategic Syrian town located near the country's border with Turkey.

But even if they're victorious when the dust settles in Mosul, Iraqi forces must still overcome the sectarian divisions that have ravaged the country.

“How do you get control when the actual population doesn’t like you very much?” Sajad Jiyad, an analyst with the Baghdad-based Iraqi Institute for Economic Reform, wondered aloud to The National.