Antifa trans militant pleads guilty in attempted arson attack at Portland ICE facility

( Post Millennial )

A 20-year-old trans-identifying Antifa militant, Alistair Macfarlane Sidener, has pleaded guilty to federal charges stemming from a violent attack on a US Immigration and Customs Enforcement (ICE) facility in Portland last year. Sidener admitted to damaging federal property during the June 12, 2025, incident, where militants attempted to set the building ablaze and vandalized video surveillance equipment.

Sidener pleaded guilty to one count of depredation of government property on Wednesday in the US District Court in Portland. He faces a maximum sentence of 10 years in federal prison, a $250,000 fine, and three years of supervised release, according to court documents.

The plea comes amid ongoing federal and state prosecution related to Antifa-linked violence in Portland. Sidener, who identifies as transgender, was arrested by the FBI on October 17, 2025, at his home following an investigation into the attack. Federal authorities said that Sidener and others targeted the ICE facility on Macadam Avenue, causing significant damage to cameras and attempting to ignite fires. Surveillance footage captured Sidener striking cameras with a large metal pole and setting debris on fire that had been placed against the facility's metal gate, which controls ingress and egress, according to court documents.

Sidener has additional open criminal cases in the state stemming from his involvement with Antifa direct actions. In January 2025, Sidener was arrested by the Portland Police Bureau for his role in a Rose City Antifa Inauguration attack in downtown Portland. He was booked into Multnomah County Jail on January 21 on charges including criminal mischief and resisting arrest. Sidener was quickly released from custody, records show.

On August 8, 2025, Sidener was convicted of second-degree criminal mischief after pleading guilty following a plea deal, which dismissed the charge for resisting arrest, court records show. Multnomah County Judge Leslie Bottomly sentenced Sidener to just one day in jail.

Sidener will be sentenced on May 27 at the Mark O. Hatfield Courthouse in downtown Portland.