Washington, Sep 18 : US President Donald Trump on Thursday (Indian time) officially designated Antifa as a "major terrorist organisation", days after the killing of his close aide and right-wing political activist Charlie Kirk.

"I am pleased to inform our many USA Patriots that I am designating Antifa, a sick, dangerous, radical left disaster, as a major terrorist organisation. I will also be strongly recommending that those funding Antifa be thoroughly investigated in accordance with the highest legal standards and practices. Thank you for your attention to this matter!" Trump wrote in a post on his social media platform, Truth Social.

Trump did not elaborate on what parameters his administration would use to make the characterisation and what actions he would take to target a left-leaning movement. Antifa does not seem to have a centralised structure or any defined leadership.

Last week, the US President repeatedly blamed the left for rising political violence in the country, including for the murder of conservative commentator Charlie Kirk.

"I'll tell you something that's going to get me in trouble, but I couldn't care less. The radicals on the right oftentimes are radical because they don't want to see crime. The radicals on the left are the problem, and they're vicious and they're horrible and they're politically savvy," he said in an interview with Fox News.

On Tuesday, prosecutors in Utah charged Tyler Robinson, the main accused in Kirk's killing, with aggravated murder and six other charges and announced that they will seek the death penalty.

According to the prosecutors, Robinson's mother told investigators that "over the last year or so, Robinson had become more political and had started to lean more to the left -- becoming more pro-gay and trans-rights oriented."

The document also noted that the mother stated Robinson had begun dating his roommate, a biological male transitioning to become a woman.

Kirk, who was 31 years old, was delivering remarks during a campus event at Utah Valley University on September 10 when he was shot in the neck. He was rushed to the hospital but succumbed to his injuries shortly after.

Kirk was the founder of Turning Point USA (TPUSA), the country's most prominent conservative student organisation.

He launched the Arizona-based group in 2012 at the age of 18, building it into a political powerhouse with over 800 chapters across US colleges.

TPUSA became a central force in mobilising young conservative voters, particularly in the 2024 election, where it played a pivotal role in boosting Trump's re-election campaign.

/IANS