An Ohio man who trained with al-Qaeda terrorist tried to play off his time abroad as a harmless holiday when questioned by his friends, authorities said. 'I'm chilling in Istanbul,' Abdirahman Sheik Mohamud wrote a high school friend on Facebook. 'Just a vacation.' But federal prosecutors charging Mohamud with supporting terrorism and making false statements say he was actually being instructed to carry out a terrorist act in the United States. Scroll down for video . Abdirahman Sheik Mohamud, 23, faces charges for attempting to provide and providing material support to terrorists, attempting to provide and providing material support to a designated foreign terrorist organization, and making false statements to the FBI . He pleaded not guilty to the charges Friday in a Columbus . federal court. Mohamud, 23, a naturalized American, had . been instructed by a Muslim cleric to return to the United . States and carry out an act of terrorism, a federal indictment . said. It said Mohamud had told an associate that he wanted to go . to a military base in Texas and 'kill three or four American . soldiers execution-style.' Before traveling from the United States to Syria, Mohamud . had posted material on social media promoting symbols of the . Islamic State militant group, the indictment said. However, a law enforcement official told Reuters that once . in Syria Mohamud and his brother, Aden, trained with the Nusra . Front, the local affiliate of al Qaeda. In Syria he sent videos of himself to an unnamed person, the . indictment said. In one video, he pointed to a gun in a holster . on his hip ,and in another he stood in front of a white house . with a black flag on it. Mohamud's brother, Abdifatah Aden, was killed fighting with the Nusra Front, . according to the indictment. NBC reports that a 17-year-old cousin of Mohamud's in the United Kingdom said that Mohamud's older brother had arrived in Syria 'to help out the oppressed Muslims there.' However neither brother showed any signs of hating their adopted country. '(Mohamud) loved Americans," he said. 'He was one of them.' Yet another brother, Abdiqani Aden, has also been arrested and after being accused of making a threatening gesture at a guard while visiting his brother in prison. Such accusations are completely foreign to friend Mohamed Elrayah, who had gotten the 'I'm chilling' years after the two lost touch. 'He did normal things — basketball, go to the park, go to the movies on Fridays,' Elrayah told NBC News. 'Everyone loved being around him. He was a nice person.' Elrayah, three years Mohamud's senior at school, did not recall the accused terrorist-in-training as a particularly religious man when they first met. However in 2011, he says he say his friend growing a long beard. 'I asked him about it and he said, 'Well, I'm kind of religious now,'' Elrayah told reporters, adding that he did not see the new religious interest a sign of being radicalized. In fact, he said he was astonished to hear of the charges. 'I would like to ask him, 'What happened?' I just keep thinking, 'What happened to this kid?'' Elrayah told reporters. Mohamud's friends expressed shock the man they knew as a normal, likable student would want to harm the country they believed he'd embraced as him home . Upon his return to the United States, authorities said, Mohamud told . an unidentified person that while in Syria, he had been trained . in shooting weapons, breaking into houses, using explosives and . engaging in hand-to-hand combat. According to the indictment, Mohamud 'wanted to kill . Americans, and specifically wanted to target armed forces, . police officers or any uniformed individuals.' The indictment . said Mohamud's plan was to attack a U.S. military base but that . he also had a backup plan to attack a prison. Mohamud also waived a detention hearing on Friday, and will . remain in custody, court documents said. His trial is set for . June 22. The three brother's mother was widowed last year, and is struggling to comprehend what has happened in her family. 'It's tragic for her,' said Hassan Omar, director of the Somali Community Association of Ohio. The larger Somali community in the area is also worried about how this will reflect on the nation's second-biggest community of such immigrants outside of Minnesota. Roughly half-a-dozen men there were indicted last week after being accused of working to support ISIS. 'We came barehanded from refugee camps. We created 4,000 businesses in Columbus. We have 3,000 or 4,000 kids who have graduated from high school and college,' Omar told NBC. He added: 'This kind of terrorist, or ISIS or Shabab is destroying our image.'
Abdirahman Sheik Mohamud, 23, is charged with supporting terrorism and making false statements by federal prosecutors .
Classmates expressed shock, remembering him as a normal and likable high school student who was not deeply religious .
Mohamud, 23, a naturalized American, had been instructed by a Muslim cleric to return to the United States and carry out an act of terrorism .