The Islamic State (IS) has a stronghold in Iraq and Syria, but a recent report indicates that the terror threat could be a lot closer to home.

A conservative watchdog group reported Tuesday that the militants are operating a training site near the Texas-Mexico border, and are smuggling their fighters into the US.

The Judicial Watch cited an anonymous Mexican Army officer and police inspector as sources for their chilling discovery.

According to the Mexican authorities, drug cartels are alleged to be assisting IS in sneaking their fighters across the border and into Fort Hancock, Texas and other locations. Mexican officials found possible evidence of IS training sites—written in Arabic and Urdu— in the Anapra neighbourhood of Juarez. The city is less than 10 miles from Texas.

The US State Department and the Department of Homeland Security (DHS) did not immediately respond to a request for comment from Fox News.

A Texas Department of Public Safety bulletin released to state law enforcement in August indicated that IS was taking an increased interest in crossing the southern border to initiate a terrorist attack.

"Social media account holders believed to be ISIS militants and propagandists have called for unspecified border operations, or they have sought to raise awareness that illegal entry through Mexico is a viable option," the bulletin read.

Over 30 Twitter and Facebook posts discussed penetrating the US through the southern border in one week. No specific target or plot was uncovered through IS' social media messaging, and DHS Secretary Jeh Johnson confirmed that his agency and the FBI were "unaware of any specific, credible threat to the US homeland" from IS.

However, The Judicial Watch warned even then that the militants were in Juarez, and planning to attack the US using car bombs.