An American soldier is now in pretrial confinement over an attack that left four troops injured

A United States airman is in military custody for suspected involvement in an insider attack on an American base in Syria earlier this year, the Pentagon said, noting that the man is likely to be charged sometime in the coming weeks. 

Air Force spokeswoman Ann Stefanek announced the arrest on Tuesday, telling CNN the soldier, who has not been publicly identified, was placed in custody earlier this month at the behest of his commander.

"As part of an ongoing investigation, on June 16, an Airman was taken into custody stateside in conjunction with the attack in Green Village, Syria. After reviewing the information in the investigation, the Airman's commander made the decision to place him in pretrial confinement," she said, adding that while it's "too early in the process" to speak of an indictment, the "expectation is charges could be filed within the next few weeks."

Officials initially believed the April 7 attack was the result of indirect artillery or rocket fire on a US base in northeastern Syria, where American forces have closely cooperated with local Kurdish fighters. Earlier this month, however, the Pentagon indicated a US service member was a "possible suspect" in the case, saying it found evidence of the "deliberate placement of explosive charges," though offered few other details.

According to two officials cited by CNN, the explosives used in the attack were "not insignificant" and had more detonation power than a hand grenade, while one official deemed them "military grade." 

The blast erupted at the facility late at night, and security footage reportedly shows an unidentifiable figure moving quickly across the frame in two instances. It is unclear if the clips depict the same individual. 

The four soldiers injured in the blast were treated for traumatic brain injuries, but none were seriously harmed and all returned to duty within weeks of the incident.

The Joe Biden administration acknowledges a deployment of around 900 American troops in Syria - most stationed in the country's northeast - despite objections from the government in Damascus, which has repeatedly complained of the years-long US troop presence.