The United States has revoked the visas of six foreign nationals on account of social media comments “celebrating” the assassination of conservative activist Charlie Kirk, the State Department said on Tuesday.

“The United States has no obligation to host foreigners who wish death on Americans,” the department said in a post on social media. “The State Department continues to identify visa holders who celebrated the heinous assassination of Charlie Kirk.”

Kirk, a conservative activist and founder of the youth organisation Turning Point USA, was shot dead on September 10 while speaking at a debate at Utah Valley University’s Sorensen Center courtyard.

Police have charged 22-year-old Tyler Robinson with murder. He has been placed in custody without bail while his trial is underway.

Those whose visas were revoked for posts about Kirk’s killing are nationals of Argentina, South Africa, Mexico, Brazil, Germany and Paraguay, the State Department said.

“[The president]...will defend our borders, our culture, and our citizens by enforcing our immigration laws,” the department added.

The announcement on revocation of the visas came on the same day that Trump posthumously awarded Kirk the Presidential Medal of Freedom, the country’s highest civilian honour, on what would have been his 32nd birthday, Reuters reported.

The United States had earlier warned that it would act against foreigners “praising, rationalising or making light” of Kirk’s death.

On Tuesday, the State Department said that the Argentinian national whose visa was revoked had remarked that Kirk had “devoted his entire life to spreading racist, xenophobic, misogynist rhetoric” and that he deserved to burn in hell.

The South African citizen had allegedly mocked Americans grieving the death of Kirk, saying “they’re hurt that the racist rally ended in attempted martyrdom” and alleging that Kirk was used “to astroturf a movement of white nationalist trailer trash”.

Since the start of his second term in January, the Donald Trump administration has intensified its immigration crackdown, including increased social media vetting, the revocation of thousands of student visas and proposals to limit visa duration.