The Iraqi government appeared to be gearing up for the long-anticipated offensive to reclaim Mosul from Islamic State of Iraq and Syria (ISIS) militants, with the Prime Minister announcing a request for more U.S. troops to help in the battle.

A U.S. government official confirmed to CBS News correspondent Margaret Brennan that the American military was prepared to meet the request.

“In consultation with the Government of Iraq, the United States is prepared to provide additional U.S. military personnel to train and advise the Iraqis as the planning for the Mosul campaign intensifies,” said the official.

Mosul is the biggest urban area controlled by ISIS in Iraq -- the country’s second-largest city. It sits about 225 miles northwest of Baghdad. ISIS has controlled the metropolis since the summer of 2014.

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Iraqi officials have said they plan to retake the city by the end of the year.

If the U.S. does send additional military “advisers” into Iraq, it won’t be the first time this year it has done so.

The government said in July that 560 more troops would be deployed to help establish a newly retaken air base as a staging hub for the long-awaited battle to recapture Mosul. Defense Secretary Ash Carter made the announcement himself during an unannounced visit to the country.

Most of those troops were to be devoted to the build-up of the Qayara air base, about 40 miles south of Mosul, and include engineers, logistics personnel and other forces, Carter said in Baghdad. They were to help Iraqi security forces planning to encircle and eventually retake the key city.

“These additional U.S. forces will bring unique capabilities to the campaign and provide critical enabler support to Iraqi forces at a key moment in the fight,” Carter said in July.

American advisers have been working at brigade level with Iraqi special operations forces for months.

Mr. Obama, in April, allowed U.S. troops to assist Iraqi forces at brigade and battalion levels, where they could be at greater risk closer to the battle. They remain behind front lines. They previously had been limited to advising at headquarters and division levels, further from the battle.

For months, Iraqi Kurdish militias working with the U.S. have been pushing into ISIS territory north of Mosul.

In March this year, CBS News’ Holly Williams met some of the Mosul residents who had managed a terrifying escape from the ISIS-controlled city, and they told her people in Mosul were growing angry with the militants, and that could make retaking the city a little easier when Iraqi forces eventually begin their offensive.

Williams met one man who showed her the marks of torture; burns from electric wires on his back and arms. His only crime was smoking, illegal under ISIS rule and its harsh interpretation of Islamic law.

Another man said he had seen another Mosul resident beheaded after being caught with a cell phone SIM card. Another told us three men were caught escaping recently, and ISIS hanged them in the street.

“They’re a criminal gang,” cried one man. “We’ve been surviving on water and bread.”

“When they first came they were tough,” said another. “But now they can see that Mosul is turning against them.”