Story highlights U.S.-led coalition supplied temporary bridge for Iraqi forces to access part of city

ISIS using citizens as human shields as Iraqi forces try to retake central Ramadi, officials say

Ramadi's fall in May spurred criticism, questions about Iraq's ability to combat ISIS

(CNN) Iraqi forces sneaked across an improvised bridge Tuesday and attacked ISIS in the key city of Ramadi, the Iraqi military said, aiming to recapture the provincial capital whose fall to ISIS months ago drew U.S. criticism about Baghdad's ability to fight the terror group.

The forces, including the Iraqi military and Shiite paramilitary fighters, crossed a Euphrates River offshoot to strike ISIS in a southeastern district of Ramadi on Tuesday morning in an attempt to retake the city center, the military said. The operation could take a few days, it said.

The move is the latest in a weeks-long effort by Iraqi forces to take back Ramadi, a city of strategic and symbolic importance 110 kilometers (about 70 miles) west of Baghdad, Iraq's heavily fortified capital.

CNN does not have a presence in Ramadi and cannot confirm troop movements there.

The U.S.-led anti-ISIS coalition, which has conducted airstrikes against the terror group in Iraq since last year, supplied the temporary bridge to the Iraqis and has provided air support for the Ramadi assault, U.S. Col. Steve Warren said.