Exclusive Look at the US Forces Aiding the Fight Against ISIS ABC News' Martha Raddatz goes inside U.S. outposts near Mosul.

 -- As Iraqi troops move within just a few miles of Mosul, ABC News Chief Global Affairs Correspondent Martha Raddatz got an exclusive look at some of the U.S. outposts supporting the mission to defeat ISIS.

“What we’ve seen is the enemy is really disrupted, they are on the offensive,” Maj. Gen. Gary Volesky, the commander of U.S. ground forces in Iraq, told ABC News. “They are trying to do some spoiling attacks, but they’re not working.”

Those spoiling attacks have often been carried out by ISIS militants in suicide vehicles speeding towards Iraqi and Kurdish peshmerga troops on the front lines, and in villages and towns where ISIS militants have been able to conceal themselves.

With U.S. ground forces advising and assisting, and the U.S.-led coalition conducting airstrikes from above, the Iraqis and Kurds have been able to repel the resistance, U.S. officials said.

“What’s different this time than what was here the last time when you and I were here,” Volesky told Raddatz, referring to a trip the pair made to the region in 2009, “is this isn’t the same Iraqi army. They have been trained to do a decisive action, conventional operation against conventional forces, and they are gaining confidence. You can see it.”

One of the small outposts Volesky and Raddatz visited was built only a few days ago, and is manned by less than 200 U.S. and Iraqi personnel.

Another was originally built only 3.5 kilometers from the front lines, but as the Iraqis have advanced, it is now 22 kilometers away. But the posts were built to be movable, and when the time is right, they will move to follow the Iraqi forces toward Mosul.

From these outposts, U.S. personnel conduct intelligence, surveillance, and reconnaissance from aircraft overhead -- information gathering that is often referred to as “eyes in the skies.” U.S. troops can also fire heavy artillery with longer ranges, such as Howitzers, which can fire 105-150 millimeter shells around 20 miles. A team firing a Howitzer said their operations have been “pretty constant” since the assault began.

But as the fight gets closer to the city, Volesky said the effort will only become more difficult.

“It’s the complexity of the environment in Mosul. You know how tight those streets are, how narrow they are. And there’s a million people there,” he told Raddatz.

The Iraqi army has been spreading word to the civilians still living in Mosul not to congregate where ISIS militants are, as those areas will likely be targeted by U.S. airstrikes. U.S. forces have received indications this week that ISIS is murdering more and more civilians who refuse to fight for them.

“The closer the Iraqis get, the better it will be for the people,” Volesky said.

As ISIS has been pushed out of the villages and towns leading into Mosul, the militants have left destruction in their wake. They have burned oil fields, leaving acrid smoke clouds hanging over huge swaths of the countryside.

“It’s really disheartening to see,” Lt. Col. Shawn Umbrell told ABC News. “There are people that will come back here and they don’t know what they’re going to see when they come back. The only two buildings that were left standing in this village were two mosques, the only two buildings. Not a single wall anywhere else.”

For Volesky, that level of destruction underscores the importance of defeating the enemy to help Iraq regain stability. And the threat is not limited to Iraq. As ISIS fighters flee the area, U.S. forces have been vigilantly watching for them to attack elsewhere, keeping an eye on the future of this fight, Volesky said.

“Every time they lose a piece of key terrain or they get defeated, they try to lash out somewhere else to deflect people’s attention ... to show that they are still relevant, when in reality, they are losing," Volesky said.