The killing of conservative firebrand Charlie Kirk, allegedly by a left-wing extremist, is only the latest of several high profile political assassination attempts in the United States by both the political right and the political left. These include the attempted assassination of then-candidate Donald Trump at a Florida golf course in 2024, the murder of a state legislator and her husband in Minnesota in 2025, and attacks on the homes of Pennsylvania Governor Josh Shapiro and former Speaker of the House Nancy Pelosi.
Although violence on the political right has been common for many years, there is also an increase – albeit from low levels – of violence from the political left. Left-wing terrorism is defined here as violence directed toward the state, capitalism, or “oppression”, with key motifs including anti-capitalist or anti-imperialist views, environmental or animal rights activism, pro-LGBTQ+ commitments, anarchist or socialist belief systems, or partisan extremism in which violence is justified against political opponents perceived as advancing right-wing agendas. The usage of “left-wing” and “right-wing” here does not refer to the mainstream political parties (Democrat/Republican) but rather to ideological orientations of perpetrators of violence.
As I detail in a longer, co-authored Center for Strategic and International Studies report, the number of left-wing terrorist incidents in the United States has increased incrementally in recent years, though from a very low base and with significantly lower lethality compared with right-wing or jihadist violence. From 1994–2000 the average was approximately 0.6 left-wing incidents (attacks and plots) per year; in the following decade (2001–10) it rose to about 1.3 per year. Beginning roughly in 2016 the trend picked up further, with an average of about 4.0 per year from 2016 through 2024.
As of 4 July 2025 (before the Kirk attack), there were five left-wing attacks or plots – on that trajectory, the year was set to be the most violent for left-wing incidents in over 30 years. Beyond the raw count, the relative share of left-wing incidents is notable: in 2025, so far, the number of left-wing incidents in the United States surpassed those attributed to the violent far right, an unusual marker in the dataset.
Anti-government extremism in the past was more the realm of the extreme right, but in the second Trump administration the extreme right is more comfortable with government, while the extreme left is more hostile.
Despite the rising count, it must be stressed that lethality from left-wing attacks remains very low. Excluding the death of Kirk, since 2020 only two fatalities resulted from left-wing terrorist attacks in the United States: the December 2024 assassination of a UnitedHealthcare executive in New York, and the August 2020 shooting of a right-wing protester in Portland. This fits longer-term trends: In the past decade, left-wing attacks killed 13 people, compared with 112 for right-wing attacks and 82 for jihadist attacks.
In general, left-wing incidents have not been mass-casualty attacks but rather more precise attacks on individuals or facilities. Many left-wing incidents employ incendiary devices or arson (20 of 35 over the past decade) rather than mass-casualty tactics. When arson occurs at night, targets may be unoccupied, reducing casualties further.
Left-wing extremist actors lack the hierarchical leadership, funding, training, and global support networks that jihadist groups enjoyed in the past. They tend to operate as lone actors or small loose networks, and with limited tactical proficiency.
Two dominant ideological motives underpin the observed rise in left-wing incidents: partisan extremism and anti-government extremism. Partisan extremism involves plots or attacks against elected officials, party infrastructure, or political staff, where the perpetrator views the opposed party or actor as illegitimate or evil. For example, in January 2025, a 24-year-old woman was arrested in Washington DC, carrying two Molotov cocktails and a folding knife with the declared intent to kill senior US officials; she described one of her targets as a “Nazi.”
Anti-government extremism targets state institutions (such as immigration or law enforcement) viewed as oppressive. A notable 4 July 2025 incident saw a group dressed in black assault the US Immigration and Customs Enforcement Prairieland Detention Facility in Alvarado, Texas. Fireworks, graffiti, body armour, and AR-style rifles were found following live fire on law-enforcement officers. Anti-government extremism in the past was more the realm of the extreme right, but in the second Trump administration the extreme right is more comfortable with government, while the extreme left is more hostile.
The broader political context is also relevant: rising polarisation, mutual demonisation of the opposing party, and a small but growing minority whose radicalisation includes acceptance of partisan violence. Surveys show that by 2022, a majority of both Democrats and Republicans believed much of the opposing side to be immoral, dishonest, or unintelligent. The rise in left-wing incidents may be linked to heightened partisan conflict and to the view of the state (or governing party) as oppressive, combined with the availability of radicalising ideologies (such as anti-fascism, anarchism) and an enabling environment for lone or loosely affiliated actors.
Even though left-wing terrorism currently poses a smaller lethal toll than right-wing or jihadist violence, the rising frequency suggests that increased attention is warranted, but this should not come at the price of less monitoring of other, historically more dangerous, forms of terrorism. Authorities must ensure counterterrorism resources and capabilities are calibrated to all ideological threats – left, right, jihadist – without over-prioritising one at the expense of the others.
Government responses must distinguish between violent extremists and non-violent political actors. Overreaching against peaceful organisations risks reinforcing extremist narratives that legitimate politics is futile, pushing recruits into violence. Political leaders and civil society must explicitly condemn violence from all ideological quarters. Mainstream condemnation reduces the appeal of extremist actors, helps communities work with law enforcement, and deprives perpetrators of social legitimacy.
While left-wing incidents are increasing, the decline in right-wing and jihadist incidents may be temporary, and security officials should prepare for its return.
This article draws on my CSIS report with Riley McCabe, “Left-wing terrorism and political violence in the United States: What the data tells us”, 25 September 2025.