“I was so young I did not really understand any of it,” Matthew, now 13 and living in Florida with his father after he was flown home by the U.S. military in 2018, told the BBC.
Matthew's life changed when he was dragged by his mother, Samantha Sally, and his stepfather, Moussa Elhassani, across the border into Syria in April 2015. He was 8 years old.
He spoke of his ordeal to BBC’s Panorama and to Frontline on PBS.
"We ran across an area that was very dark,” Matthew said during the interview. “It was at night, there was a lot of random spots of barbed wire… There wasn't much going through my head except, 'I need to run.'"
Matthew, his mother, and his stepfather lived in Raqqa, the city that the ISIS terror group claimed as its capital.
"It was pretty noisy, gunshots normally," he said. "Once in a while a random explosion, like far away, though. So we didn't have too much to worry about."
His stepfather became an ISIS sniper, and the child filmed a number of propaganda videos. In one video, Matthew assembled a suicide belt; in another, he took apart an AK-47.
In the most famous video, Matthew – calling himself Yusuf – threatened President Trump.
"My message to Trump, the puppet of the Jews: Allah has promised us victory and he's promised you defeat," he said in the video. "This battle is not going to end in Raqqa or Mosul. It's going to end in your lands… So get ready, for the fighting has just begun."
Matthew said he was given no choice but to take part in the video as his stepfather was “starting to lose it” at the time, prone to outbursts of anger.
When Elhassani was killed in a suspected drone strike, Sally said she took the chance to smuggle herself and her four children out of the region.
"I was happy 'cause I didn't like him, obviously," Matthew said. "I don't think I should have been, because a person died, but I was. We were all crying out of joy."
While the family was in a detention camp, Sally started telling her story. She claimed that her husband tricked her into taking her family to Syria, that she helped him buy slaves whom he regularly raped.
Sally maintained her innocence, but a Panorama/Frontline investigation found records that indicated Sally had made a series of trips to Hong Kong in the weeks before her family left the U.S., depositing at least $30,000 in cash and gold in safety deposit boxes.
Prosecutors also found that Sally had helped to film the propaganda videos of her son.
A Department of Justice press release from 2019 said Sally – named Samantha Marie Elhassani – pleaded guilty to one count of concealment of terrorism financing.
“Elhassani admitted that she traveled overseas and pre-positioned over $30,000 in cash and gold, knowing that the funds would be used by her husband and brother-in-law to join and support ISIS in Syria,” said Assistant Attorney General for National Security John C. Demers. “The National Security Division is committed to identifying and holding accountable those who support foreign terrorist organizations.”
When asked how it felt to be back in the United States, Matthew said it was “like sweet relief.”
"It's like being in tight clothes or tight socks and shoes all day and then just taking it off and just feeling nice and chilling in a hot bath,” he said.