The U.S. State Department said on Tuesday it had revoked the visas of six foreigners over social media comments made about the assassination of conservative activist Charlie Kirk.

The announcement of the revocations came as U.S. President Donald Trump posthumously awarded Kirk with the Presidential Medal of Freedom, the highest civilian honour in the U.S., on what would have been Kirk's 32nd birthday.

"The United States has no obligation to host foreigners who wish death on Americans," the department said on X.

It listed South Africa, Argentina, Mexico, Brazil, Germany and Paraguay as the home countries of the people who had their visas revoked.

In one post, an Argentine national accused Kirk of "spreading racist, xenophobic, misogynistic rhetoric," according to the State Department. Another person, according to the department, wrote in German: "when fascists die, democrats don't complain."

The State Department added that it continues to identify visa holders who it says celebrated Kirk's assassination at a Utah university event last month.

It had previously warned that the U.S. would take action against foreigners "praising, rationalizing, or making light" of Kirk's death.

Since January, the Trump administration has pursued a sweeping crackdown on immigration, including increasing social media vetting and revoking thousands of student visas and aiming to tighten the duration of others.