The U.S. military will send 200+ more "advisory" troops, 8 Apache helicopters, and millions of dollars to Iraq as part of the ramped-up effort to reclaim that nation’s second largest city from the self-proclaimed Islamic State, the U.S. Defense secretary announced Monday.

The U.S. will provide $415 million in financial assistance to Peshmerga fighters, a Pentagon spokesman announced via Twitter. Secretary of Defense Ash Carter, who is visiting Baghdad, said the United States will also send an unspecified number of AH-64 Apache helicopters “in support of operations to retake Mosul,” his spokesman, Peter Cook, wrote in a tweet.

The department has yet to say how many more troops would be headed to Iraq or when. Officially, according to DoD statistics, there are 3,850 troops in Iraq; and this new addition would bring the tally to more than 4,000.

A senior Defense official who briefed reporters en route to Baghdad said Kurdish leaders have assured Carter that they will take part in any future Mosul operation, which likely led to the U.S. decision to provide them with additional money.

The operation to reclaim Mosul, which fell to ISIS control in June 2014, has become the keystone of the U.S. effort in Iraq. U.S. officials insist that Iraq is in the lead in the planning for that offensive, but over the past few months, the U.S. military has had an increasingly growing role in the Iraqi fight for Mosul. Last month, U.S. Marines helped the Iraqis reclaim areas south of Mosul, marking the first time that U.S. ground forces were part of offensive operations.

—Nancy A. Youssef