In response to Thursday night’s drone strike that killed Iranian General Qassim Soleimani, UN Special Rapporteur on Extra-judicial Executions Agnes Callamard said that the assassination likely violated international human rights laws.

Late Thursday evening the White House revealed that President Donald Trump had authorized a drone strike against Soleimani while the general visited Baghdad. Soleimani was the commander of the Quds Force, a division of Iran’s military responsible for undertaking clandestine military operations against other countries. Soleimani has long been a source of concern for the US government because of his ties to terrorist groups, with the administrations of presidents George W. Bush and Barack Obama having considered and rejected targeted strikes against him in the past according to AP. Trump said in a press conference that he ordered the strike against Soleimani in order to “end his reign of terror” before he could carry out any further attacks on US interests.

On Twitter, Callamard said that the strike authorized by Trump was likely illegal because the US had not demonstrated that Soleimani was an “imminent threat to life.” She said that in order for a extra-judicial killing to be legal, the US would need to show that the person being targeted was preparing to commit an act that would lead to loss of life and that “an individual’s past involvement in ‘terrorist’ attacks is not sufficient to make his targeting for killing lawful.” In addition, she said that the anticipatory self-defense asserted by Trump at his press conference is also likely not legal, since such a preemptive strike requires that there be “instant, overwhelming, and leaving no choice of means, and no moment of deliberation” before acting.

In addition to Callamard, various groups in the US like the American Civil Liberties Union and congressional members like Alexandria Ocasio-Cortez and Speaker of the House Nancy Pelosi issued statements strongly condemning the strike, echoing Callamard’s analysis that the assassination was illegal.