US | Ramifications of Charlie Kirk killing

• We have not seen any evidence that the killing of conservative activist Charlie Kirk on 10 September will prompt retaliatory violence
• So far, the calls for violence we have seen on online channels have been generic
• President Trump has not said what actions his administration will take in response to the killing, but he has blamed rhetoric from the ‘radical left’ for it

We have not seen any clear signs that the killing of conservative activist Charlie Kirk on 10 September will lead to immediate acts of vengeance. Some users of online channels have called for violent retribution against ‘the radical left’, which they have blamed for his death. But so far, the calls for violence we have seen have been generic, rather than suggestive of specific plans. And to our knowledge, neither federal nor state authorities have issued any warnings about other threats of political violence.

Still, the recent incident adds to an already-febrile political atmosphere in the US. There have been several other acts of violence against public figures there over the past year, and the extremely polarised reaction to Kirk’s killing sustains a high chance that other people will commit similar acts in 2026. It is unclear how the Trump administration will respond to the incident. But Trump’s rhetoric since the killing and that of other senior officials suggests that the administration is preparing to take steps to regulate public speech and rhetoric.

Kirk murder similar to other political killings

The available information about Kirk’s murder suggests it was similar to other attacks against political figures over the past year. The suspected shooter, who was arrested on 11 September, appears to have acted alone; on 12 September, officials said that they do not have ‘any information that would lead to any additional arrests’. The main lead in terms of his ideological convictions are anti-fascist references and messages found on some of the suspect’s unfired bullet casings.

Evidence of anti-activist campaign publicising personal information

We have become aware of a website listing the personal information of dozens of people across the US. The ‘Expose Charlie’s Murderers’ website consists of a list of people who allegedly used their social media to celebrate Kirk’s death and includes their name, location, employer and examples of their online activity. According to the site administrators, ‘this website will soon be converted into a searchable database of all 20,000 submissions,’ describing it as a ‘permanent and continuously-updating archive of Radical activists calling for violence’.

We have not seen any explicit calls for violence on the site. Indeed, the ‘about’ page carries a message denouncing ‘all political violence and criminal activity’. Based on the language used, the main intent of the campaign appears to be to pressure employers to dismiss those named.

Despite the absence of direct incitement, publicly exposing personal details in this manner heightens the risk of harassment and physical violence against those listed. Similar incidents in the US have previously led to stalking, threats and, in isolated cases, assaults by unaffiliated individuals. The probability of at least some individuals facing online harassment or real-world intimidation is therefore high in the near term, particularly where addresses or workplaces can be easily located.

No specific calls for violence more generally

Elsewhere online, some users of channels broadly aligned to Kirk’s political views have called for attacks against the ‘left’ as retaliation. For example, one anonymous user on 4chan wrote about Democrats, ‘you all need to be eradicated for the good of the republic at this point’ while another hinted at revenge saying, ‘no more turning the other cheek, it’s time for good ol’ eye for an eye’. But so far, as seen in these cases, the only calls for violence we have seen are not focused on specific individuals; rather, they are expressing a general anger at those ‘responsible’ for the attack.

Trump administration’s potential response to political violence

Other than seeking to dissuade violence reprisals, President Trump has not said what actions his administration will take in response to the killing. But he has been clear on what he blames for Kirk’s death. Shortly after announcing Kirk’s death, the president blamed rhetoric from the ‘radical left’ and said his ‘administration will find each and every one of those who contributed to this atrocity and to other political violence’.

Some of Trump’s critics have speculated that he could use the killing as a pretext to suppress his opponents. In the absence of specific announcements, such suggestions seem exaggerated at this stage. Nevertheless, it is at least plausible that the Trump administration will begin attempts to regulate what it considers to be ‘radical-left rhetoric’. In a sign of what this may consist of, Trump on 14 September said that some groups affiliated with the left are already under investigation, without providing specifics.

Trump has previously used the term ‘radical left’ to describe a wide range of individuals and organisations. These have included Democratic politicians, loosely organised groups such as Antifa and Black Lives Matter, as well as organisations across various sectors. And in particular, the president has in recent years suggested several national media outlets – such as CNN, MSNBC and the New York Times – as being part of or supportive of the ‘radical left’.

Comments from administration officials suggest any efforts would focus on scrutinising public statements that appear to incite political violence. The Washington Post cited an unnamed source familiar with the administration’s internal strategy on 11 September as saying that the next steps could be aimed at people who explicitly say they will perpetrate acts of violence.

Based on our understanding of what the administration can do constitutionally, any law or efforts to target hate speech generally would almost certainly fail because it is not tailored to a compelling government interest. Given this, the administration will probably focus on unprotected speech, specifically speech that qualifies as a threat or incitement to imminent lawless action.