An active-duty soldier -- who was separated from the service a day before the FBI arrested him Tuesday at an Army base in Hawaii -- was charged for repeatedly striking a police officer with a flag during the Jan. 6, 2021, U.S. Capitol riot, according to court records released this week.
Alexander Cain Poplin, 31, was arrested at Schofield Barracks this week after the FBI received a tip a month after the riot implicating the former soldier in the assault. Poplin was not in the military at the time of the riot, but later joined the Army after earlier service in the National Guard, Army officials said.
An Army official told Military.com on Thursday that Poplin was separated from the service a day before his arrest despite being apprehended on the base. The Justice Department charged him with three misdemeanor offenses, including entering restricted grounds, disorderly conduct and engaging in physical violence.
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"Pvt. Alexander Cain Poplin served in the Army National Guard as a 91J quartermaster and equipment repairer from December 2012 to December 2018, and obtained the rank of specialist," Bryce Dubee, a spokesperson for the Army, told Military.com on Thursday. "He later began active-duty service as an 11B infantryman in April 2023 and was assigned to the 25th Infantry Division in September 2023. Pvt. Poplin has had no deployments during his military service."
Dubee would not comment on the nature of Poplin's separation, citing Privacy Act concerns.
Poplin had been on the FBI's radar since February 2021, according to court records. Army officials did not immediately respond to questions about how Poplin was able to join the active-duty military while under investigation, but it appears that the FBI did not identify him as a soldier until this summer, court records indicate.
Through video and images, the FBI observed Poplin at the Capitol wearing a black jacket, beanie, medical mask and an Army-camouflage backpack. Throughout the day, he was observed carrying multiple flags, including a blue Trump 2020 flag, court records said.
Court documents allege that Poplin repeatedly struck a Metropolitan Police Department officer with a blue flag that afternoon. Footage from body-worn cameras and open-source video captured the assault, the Department of Justice said in a release Wednesday.
"Court documents say that Poplin's alleged actions at the Lower West Plaza contributed to the chaos as rioters confronted law enforcement officers who were defending the Capitol," the release said.
After the riot, court records allege that Poplin boasted about the assault on social media, stating that "we beat their f---ing ass and stood for something" and "we took our house back."
The listed attorney for Poplin was unavailable to comment about her client's arrest this week after Military.com called her office Thursday.
The George Washington University Program on Extremism previously reported that more than 100 Jan. 6 defendants had known military connections, to include veterans, National Guardsmen and a handful of active-duty service members. According to the program, that accounts for 12% of defendants involved in the riot.
Related: 5th Active-Duty Service Member Arrested on Jan. 6 Charges