A man sits under a sign with flag belonging to the Islamic State in Iraq and the Levant (ISIL) along a street in the city of Mosul June 12, 2014.
IN PHOTO: A man sits under a sign with flag belonging to the Islamic State in Iraq and the Levant (ISIL) along a street in the city of Mosul June 12, 2014. REUTERS/Stringer REUTERS/Stringer

ISIS has claimed they have trained dozens of militants in 15 states in the U.S. The extremist group has put an unverified warning message on the Internet and suggested that more bloodshed will come following the attack in Garland, Texas last weekend.

ISIS had previously took the credit for the shooting attack in Texas but the White House and other security experts are doubtful of the group’s claim. The U.S. officials said the militant group has yet to provide evidence of it’s alleged direct involvement after two suspected extremists were shot and killed by police.

The Mirror reports that ISIS has boasted in a file-sharing site favoured by ISIS supporters that it has “signed up” 23 new fighters for the U.S. attacks similar to Texas. The message was signed by Abu Ibrahim Al Ameriki. Authorities believe he is the same man who appeared in ISIS’ previous propaganda videos.

“Out of the 71 trained soldiers 23 have signed up for missions like Sunday, we are increasing in number. Of the 15 states, 5 we will name… Virginia, Maryland, Illinois, California and Michigan,” read the posted message. The warning went to say that the “brothers” police killed had given their bodies in plain view because ISIS was watching.

FBI director James Corney said in February that the agency is investigating in every state for possible signs of terrorist "sleeper cells." He believes each state in the U.S. has homegrown violent extremists. An intelligence official told Fox News that U.S. officials were investigating the threat but finds it difficult to believe it came from the leaders of ISIS. The online threat may have come from a low-ranking fighter taking advantage of the incident in Texas.

An intelligence spokesperson said the U.S. does not take terror threats lightly. ""The U.S. takes any threat to its citizens and our national security seriously, and we expect ISIL and its supporters to continue their efforts to incite fear and encourage lone wolf attacks around the world," the spokesman said.

ISIS training new recruits is nothing new as an Iraqi human rights commission suggests the terror group is teaching 1,000 children in the last six months to become suicide bombers. Fadhil Kharawi, a member of the Iraqi Independent Commission for Human Rights, told reporters in Baghdad that ISIS militants have trained the children since last November.

The training of child suicide bombers is reportedly part of the “Cubs of the Caliphate” centre in ISIS’ stronghold of Mosul in Iraq. Other children have been forced to attend the ISIS training camp after schools were shut down by militants.

Meanwhile, ISIS has posted photos of its newly opened luxury hotel for militants in Iraq. Images of militants sprucing up the building and grounds were released online. The five-star hotel boasted of 262 rooms, two restaurants, two ballrooms, a gym and a swimming pool, reports the Mirror. The hotel is believed to be the former Ninawa International Hotel.

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