As Iraqi forces edge closer to the last remaining ISIS stronghold in the country, cooperation and support from civilians trapped inside is a key to the operation's success.

Despite the Islamist terror army’s well-documented atrocities, it's not a given that citizens will rise up against them. When Iraqi Forces encircled the village of Tel Kaif on Sunday, "waves of civilians" walked toward them, according to a military official. Although they appeared to be fleeing and praised the liberators, it may have been a trap. ISIS fighters moving behind them used the citizens to mask a bloody ambush.

"It's a human shield in some ways," one official said. "But it also shows the depths of the ideology. ISIS will go, but the ideology is a much harder war to win."

SNIPER OF MOSUL TERRORIZES ISIS

Tel Kaif -- also known as Tel Keppe -- is a historically Christian farming town located just northeast of Mosul. As of 2004, its population was half Christian and half Muslim, but the former gradually declined in the ensuing years. In early August 2014, ISIS overran the region, prompting the remaining Christians to flee or face slaughter.

This leaflet dropped by Iraqi forces warns civilians that the government, not ISIS, is their protector. (FoxNews.com)

Civilian support for ISIS isn't isolated. Large pockets of Arab areas and Sunni villages around Mosul still view ISIS as a better alternative to Iraq's Shia government.

Over the weekend, the oil-rich city of Kirkuk lit up with gunfire after an ISIS sleeper cell was activated, as snipers and would-be suicide bombers stormed the streets. It was quickly revealed that almost all participants in the cell were from neighboring Arab villages, and had come to the Kurdish-controlled territory claiming to seek asylum from the conflict.

"This is a big problem for us; even we were surprised by the support," said Adnan Kocher, senior adviser to Lahur Talabani, head of intelligence and counter-terrorism for Kurdistan. "This kind of ideology is a disease. We have been dealing with it for years now."

INSIDE ISIS' TUNNEL SYSTEM

However, Baghdad is working overtime in an effort to convince residents in and around Mosul -- in areas still monopolized by the black-clad jihadist army -- that the government will be their just protectors, and that the jihadists will not evade punishment.

"Warning: for all Iraqis who are involved with ISIS, ISIS is over and there is no return," reads a leaflet obtained by FoxNews.com, which was dropped from the sky by Iraqi Forces and features the national flag on one side and harsh words of caution to terrorists on the other. "For those who are seeking mercy and amnesty, they have to capture an ISIS, either Arab or foreigner, and turn him into the hands of security forces or else you will be killed.

“ISIS brought destruction to your sweet cities," the flier adds. "Your government is more merciful and Iraq is the one who takes care of you."