Killing of Charlie Kirk spurs renewed focus on left-wing extremism as CSIS reports 30-year high

Conservative activist Charlie Kirk was assassinated Sept. 10 while addressing an audience at Utah Valley University in Orem, Utah. Prosecutors charged 22-year-old Tyler Robinson with murder in Kirk's death as the campus event concluded. The killing comes as researchers report a surge in left-wing violence, with a Center for Strategic and International Studies study showing 2025 on track to be the left's most violent year in more than three decades. The CSIS analysis tracks 750 incidents of left-wing extremism in the United States from 1994 through July 2025 and notes that left-wing attacks and plots have begun to outnumber those linked to the far right for the first time in more than 30 years, even as overall lethality remains comparatively low.

CSIS defines terrorism as violence or threats by nonstate actors intended to achieve political goals and spread fear. Analysts say the rise on the left is driven mostly by attacks on government facilities and partisan plots aimed at conservative leaders. As the report notes, despite the rise in incidents, the lethality of left-wing attacks remains very low. One example came on July 4 when a group of black-clad suspects armed with rifles and fireworks stormed the ICE Prairieland Detention Facility in Alvarado, Texas. Prosecutors say the attackers sprayed anti-ICE graffiti, shot a police officer in the neck and exchanged fire with correctional officers before fleeing. Fourteen suspects have since been charged with attempted murder of federal officers and firearms offenses. In January, Capitol Police arrested Riley Jane English, 24, on the National Mall. Court documents show English was carrying a folding knife and two Molotov cocktails and had threatened to kill top Republican officials, including Secretary of War Pete Hegseth, House Speaker Mike Johnson and Treasury Secretary Scott Bessent.

Kirk's assassination is the most high-profile attack in this surge. Federal prosecutors allege Luigi Mangione carried out the assassination and charged him with murder, stalking and firearms violations. A judge later threw out terrorism charges, but the Justice Department has described the case as politically motivated. Kirk's death has already reverberated beyond Utah: a memorial service at State Farm Stadium in Glendale, Ariz., attracted supporters who wore hats bearing slogans such as Make America Charlie Kirk.

Other episodes cited in the CSIS report include an arson attack in March on the Republican Party of New Mexico headquarters, leaving graffiti that read ICE = KKK. Since 2020, only two people have been killed in left-wing attacks prior to Kirk's death, Aaron Danielson in Portland in 2020 and UnitedHealthcare CEO Brian Thompson in December 2024. By comparison, right-wing terrorism has caused higher death tolls in recent years. The lull could be temporary, researchers say. Analysts urge vigilance in how leaders respond, warning that sweeping crackdowns on nonviolent groups risk fueling more extremism. The CSIS study concludes that U.S. political leaders and activists need to condemn violence on their side and call for calm when violence involves opponents.

Experts say the spike in left-wing violence could complicate security and law enforcement priorities, even as officials stress the need to protect civil rights. The CSIS report cautions that ignoring the trend would be a dangerous mistake, and that punishment-focused approaches to nonviolent groups could backfire by widening grievances and driving more covert actions.

Kirk's death and the Mangione case have underscored a broader challenge for U.S. political life: how to address violent extremism without inflaming it. As investigations continue, CSIS researchers say the country faces a balancing act between monitoring threats and avoiding heavy-handed moves that deepen mistrust on both sides.