This article is part of a Fox News Digital series examining the consequences of the U.S. military withdrawal from Afghanistan one year ago this week.

NORCO, Calif. — Shana Chappell woke up crying.

"I felt really uneasy, but I thought it was just in my head," she told Fox News.

Chappell thought she needed to clear her head, so she took a Marine flag her son, Lance Cpl. Kareem Nikoui, left at home while on deployment. She attached it to her truck and drove around.

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Lance Cpl. Kareem Nikoui, who was killed in Kabul

Lance Cpl. Kareem Nikoui was one of the 13 American heroes killed in the August 2021 suicide bombing at the Kabul airport during the United States' evacuation of Afghanistan. (Courtesy Nikoui's family)

But then she got home and started scrolling Instagram. That's how she learned there'd been an explosion at the Kabul airport.

"I recognized the background picture from a video Kareem had sent me a few hours prior," Chappell told Fox News. "I immediately started texting Kareem and asking him to please text me, to let me know he was all right."

Nikoui, 20, was among the 13 U.S. service members killed on Aug. 26, 2021, at Hamid Karzai International Airport during the U.S. withdrawal from Afghanistan. The blast also killed at least 170 Afghan civilians and injured more than 150 others. 

‘Our country is worth fighting for’

Nikoui was outgoing as a child.

"He wanted to be everybody's friend," Chappell told Fox News.

An athlete, Nikoui played football, soccer and baseball. When he got older, he got into boxing, kickboxing, MMA and even became a jiujutsu champion.

But ever since he was a toddler, he wanted to become a Marine.

"We went to the mall, and there were actually some Marines there in their dress blues," Chappell told Fox News. "From then on, Kareem’s little army men he had at home became Marines."

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Nikoui pictured with his mother

Nikoui wanted to become a Marine ever since he was a toddler, his mom, Shana Chapell, left, says. (Courtesy Nikoui's family)

"From then on, that was just something he talked about becoming," she added.

Chappell felt like her little boy was leaving when he finally went off to boot camp. But "after he graduated, it was like I got a little man back," she said.

"He stayed himself. He just acted more mature," Chappell told Fox News. "He was kind of like a boss."

Nikoui regularly called his mom while he was on deployment. Because he was in Jordan, Chappell didn't worry much.

During one call, Nikoui told Chappell he'd be home in about a week. But a few days later, he called again and said he was getting sent to Kabul to help with the Afghanistan evacuation.

"Then I started worrying," Chappell told Fox News.

After seeing the Instagram posts on Aug. 26, Chappell watched the coverage of the Kabul explosion with her daughter. Chappell had her daughter turn off the news when reports started coming in that several service members were killed.

"I told her, you know what? One of those won't be Kareem," she said. "He's going to be fine. He's going to be home."

"And then I went about my day waiting to hear from Kareem," Chappell continued.

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Nikoui on horseback

Nikoui had an athletic childhood, playing numerous sports. He later became a jiujutsu champion. (Courtesy Nikoui's family)

Nikoui's father was the one to tell Chappell that her son was killed in what was later confirmed as an ISIS-K terrorist attack.

The fallen Marine used to hike the hills behind his house to train and would always stop on one in particular. His grave overlooks that hill.

"I chose this spot because it faces someplace he spent a lot of time," Chappell told Fox News.

"Kareem's Marine brothers have been very supportive since they all got back from Kabul," she said. "They've been with me almost every single weekend."

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Chappell said they'd tell her funny stories about her son or would describe the way he helped others while on deployment.

"It just helped me out a lot to know that Kareem was so highly thought of and loved by his Marine brothers," Chappell told Fox News. She said being "around people who were being strong so they could help me be strong" helped her pull through that hard time.

Nikoui "believed that our country is worth fighting for," Chappell said. "He believed that maybe becoming a Marine, there was something big he was going to do to help better our country."