Terrorists are using people as human shields and executing those trying to flee or surrender to slow down the Iraqi Army’s operation to recapture Fallujah. The country security forces are following a special plan to avoid unnecessary civilian loses.

Although the offensive to recapture Fallujah was launched on Monday, Iraqi government forces have been besieging the city and its suburbs for several months now, carefully devising a plan to save civilians trapped in the urban area since January 2014, Iraq’s Foreign Ministry spokesman, Ahmad Jamal, told Izvestiya daily.

Noting that one of the main goals of the military operation was “to minimize possible losses among the civilian population,” Jamal said that the active phase was preceded by surgical strikes on Islamic State (IS, formerly ISIS/ISIL) positions by the Iraqi Air Force.

“At the moment, the main difficulty lies in the fact that ISIS militants use residents as human shields,” Jamal said. “The greatest threat to the residents of the city comes first of all from ISIS militants whom the ordinary people have to deal with every day. It is no secret that extremists during their presence in Fallujah staged mass executions and made a number of other crimes against humanity.”

According to United Nations estimates, there are about 60,000 to 100,000 civilians remaining in Fallujah. People trapped in the city told USA TODAY that as the army advances, Islamists imposed a curfew on civilians and moved people to the city center to use as a human shield. IS also prevented civilians from leaving the city and threatened to kill anyone attempting to escape.

READ MORE: Iraq kick-starts op to retake Fallujah from ISIS as residents evacuate

On Sunday, the Iraqi government deployed at least 20,000 troops and Popular Mobilization Forces to combat extremists, and told residents to flee the city ahead of the operation, that was launched the following day.

By the end of Tuesday, according to the Kurdish Rudaw news agency, three villages of Haswahm, Albu Awda and Abbasian had been liberated from the terrorists. The Anbar provincial council announced that the Iraqi Army is less than a kilometer away from Fallujah, which has an estimated 800-1,000 IS fighters.

US Defense Secretary Ashton Carter said on Tuesday that Washington supports the Iraqi operation, and promised to help if necessary.

“The Iraqi forces have this planned out,” Carter said. “We are privy to those plans. We are obviously supportive of this operation.”

READ MORE: Fallujah civilians told to flee as Iraqi troops prepare to attack ISIS

“The commanders there have not brought any request from the Iraqis,” he added. “We’re always willing to doing additional things.”

Fallujah which sits just 40 mile away from Baghdad is believed to be heavily mined and full of IS snipers.