Mile-long underground ISIS training camp uncovered outside of Mosul.

The interior of the underground Tadmour Base that Iraqi army commanders claim was used by ISIS militants to train foreign fighters and teens in southern Mosul was discovered.

Iraqi commanders said there is evidence of ISIS using the base to train foreign fighters, children and teens for bombings and warfare.

It is near the airport, south of the city. And to enter the fortified base, which is 10 meters underground, one must walk through a tunnel.

It was discovered by the elite Rapid Response force.

“It is designed as part of the training,” on Iraqi commander told Rudaw. “The trainees, as part of their programs, should crawl onto these barrels and get themselves in the mud to pass this phase of training. As you see power has been extended to lighten this base. They have fully equipped it without any shortcomings. The majority of those who used to undergo training here were foreigners.”

The facility was previously constructed by the Iraqi government as a railway tunnel.