The State Department said Tuesday it has revoked the visas of six people for making incendiary social media comments about the assassination of conservative activist Charlie Kirk.

The six people — none of whom were named — hailed from Argentina, South Africa, Mexico, Brazil, Germany and Paraguay, the department said in a series of . Some of them made comments that suggested Kirk deserved to be killed.

"The United States has no obligation to host foreigners who wish death on Americans," the State Department wrote on X. "The State Department continues to identify visa holders who celebrated the heinous assassination of Charlie Kirk."

The State Department did not specify whether any of the people are currently in the U.S. or what types of visas they held. CBS News has reached out to the department for further information.

A day after Kirk was killed on a Utah college campus, a top State Department official "appropriate action" against any visa-holders who praise or make light of Kirk's death — and invited people to send in any concerning posts that they see. 

Days later, Secretary of State Marco Rubio , "visa revocations are under way."

Kirk was shot and killed on Sept. 10 while speaking to students at Utah Valley University for an event put on by Turning Point USA, a group he co-founded. Authorities said the gunman shot Kirk using a rifle from the roof of a nearby campus building. 

Following a two-day manhunt, a 22-year-old Utah man identified as Tyler Robinson was arrested in the killing. State prosecutors have charged Robinson with aggravated murder. 

The revocations are part of a wider crackdown on comments that mock or celebrate Kirk's death. The Pentagon and the Secret Service have sidelined service members or agents who wrote negative social media posts about Kirk, and Vice President JD Vance has encouraged people to call the employers of anybody who celebrates Kirk's killing.

The Trump administration has sought to revoke visas in other circumstances, too. It is pushing to deport several international students who are linked to campus protests against Israel's war in the Gaza Strip, accusing them of antisemitic rhetoric, which the students have denied. And it Colombian President Gustavo Petro's visa last month for encouraging U.S. troops to disobey President Trump's orders during a protest in New York.

Social media comments are also being monitored by the U.S. Citizenship and Immigration Services, the agency responsible for processing immigration and naturalization applications. In August, USCIS directed its officials to investigate applicants for "anti-American views and activities."

"There has been such a large-scale espousing of foreign terrorist ideology, whether it's Hamas or another organization, that has been matched with a clear desire by these elements to trample on the right of other people around them," USCIS Director Joseph Edlow told CBS News in an interview on Wednesday.

When asked whether he's talking about legally protected speech, Edlow said, "People are free to make whatever statements they want on social media or anywhere else and anyone who, you know, doesn't support the same candidate that I support."

"That is not what we're talking about here ... we're talking about people who are actively supporting that violent overthrow of this country or otherwise providing material support to terrorist organizations across the world," he added.

The government's legal power to deny or revoke visas on speech grounds is an unresolved question, , a UCLA professor emeritus of law who has written extensively about the First Amendment, told CBS News last month. The Supreme Court has that the government has broad latitude to refuse to admit people into the country, but whether federal officials can deport people who are already in the U.S. due to their speech is less clear.

Volokh said noncitizens "have the same First Amendment protections against, say, criminal punishment or civil liability as citizens do."

"But when it comes to the question of deportation or exclusion from the country in the first place, the rules turn out to be unsettled," he said.