He said he has been called all kinds of names by his fellow soldiers -- raghead, sand monkey, Zachari bin Laden.
"They're all terrible names, but the one that really hits me hard is to be called a terrorist," Klawonn said. "My heart drops every time I hear that."
Klawonn said he reported the incidents and others to his superiors, and he was shuffled around to other bases.
When asked about Klawonn's case today, the Army provided a statement to ABC News: "Senior Army leaders were unable to comment on the story because of the ongoing investigation. ... Army officials who viewed the [ABC News] piece applauded his candor, and that of his fellow soldiers, in telling his story."
Klawonn said he was transferred to Korea for a time, and then returned to Fort Hood with his unit in December 2008.
In his third week at Fort Hood, Klawonn said, he was walking out to his truck when he saw a piece of paper tucked underneath the wiper on his windshield.
"I took the letter out, read it, and it said, 'Hey carpet jockey, go back where you came from,'" Klawonn said.
The alleged discrimination at Fort Hood didn't end there, according to Klawonn. The name-calling continued, Klawonn said, adding that he even had a bottle thrown at him from a passing car when he was wearing his religious robes.
Nearly a year after Klawonn arrived at Fort Hood, on Nov. 5, 2009, Maj. Nidal Hasan, a Muslim, opened fire at an Army processing facility on base. He killed 13 people and wounded dozens more.
Klawonn had never even heard Hasan's name, but he knew that Hasan's crime would result in more problems for him.
"I knew people were going to immediately and automatically draw a comparison between us, just due to the fact that we were both Muslim," he said. "There was a vibe that people weren't coming around to talk with me, and they really asked me to justify the situation, you know, why he did that."
"I felt like there was a lack of trust within the group around me," Klawonn said. "I heard rumors. You know, 'Watch Klawonn, see what his friend did? See what his brother did?'"
Then in February, someone did more than just call him a name, he said. At 2 a.m. on a Monday, Klawonn said, he was startled from his sleep by a loud beating sound on his door. Someone was kicking the door so hard, he could almost feel it in his bed. At first, he thought it was some kind of fire drill, but then he cracked open the door.
"A note falls that was wedged in the door," he said.
It read, ''F--k you raghead, burn in hell."
Klawonn said he went running through the hallway, trying to catch the person who did it, with no success. He reported the incident to his commanders, and he said their solution was to have him move off base for his safety.
He does feel safer, but he's frustrated by the way he said the Army has handled the harassment.
"I've filed complaint after complaint," he said. "There's really no closure or justice with any of the cases. I state my problem, they say there'll be an investigation that's ongoing, and then it's kind of swept under the rug."
After the February incident, Klawonn was given 10 days of leave and went home to Florida. There, for the first time, he shared his experiences with his family.