Immigration and Customs Enforcement declared that its agents were diligently at work enforcing “400+ federal laws” to prevent the following from crossing “the border illegally”: people, money, products and ideas, in a post to social media site X that was deleted hours later on Thursday.

“Ideas?” you ask.

It appears that the country’s primary immigration enforcement agency has, at least briefly, declared itself the border thought police. In a country that is supposed to believe in the freedom of speech and thought, this raises a host of questions.

What ideas does ICE believe are illegal? How can ideas even cross the border illegally? And how does ICE screen for these illegal ideas to stop them from coming in?

ICE did not immediately respond to a request to answer these questions or why the post was deleted, but based on the Trump administration’s early actions, including stripping visas and green cards from students, denying entry to foreign visitors and arresting and deporting people for their opinions, it is clear what ideas it may deem “illegal.”

Chief among them is any criticism of Israel. The administration has sought the deportation of numerous students for their participation in or support for protests against Israel’s war in Gaza. The most high profile of these cases are those of Columbia University student Mahmoud Khalil and Tufts University student Rumeysa Ozturk.

Khalil, a legal permanent resident, was a spokesperson for the student protests against Israel’s war in Gaza. He had never been arrested or found to have participated in any act beyond his free exercise of speech. The administration stripped him of his legal status, arrested him and moved to deport him.

Similarly, Ozturk, who is on a student visa, merely co-wrote an op-ed in her student paper calling for the university to follow a student resolution to divest from certain companies involved in Israel. She was stripped of her student visa, picked up by unidentified ICE agents off a street in Massachusetts and whisked to a detention facility in Louisiana.

Like Khalil, the administration is seeking to deport Yunseo Chung, a 21-year-old Columbia University student and legal permanent resident who moved to the U.S. from South Korea when she was 7 years old. Chung was stripped of her legal status for participating in protests against the war in Gaza and is challenging her case in court. She won a temporary restraining order March 25 blocking her detention while her case moves forward.

These are only three of dozens, if not hundreds, of similar cases where visa holders and legal residents are being punished for their ideas.

The administration explicitly states that Khalil and others are being deported for their ideas. In a letter to the court hearing Khalil’s case sent April 9, the State Department declared that Secretary of State Marco Rubio moved to strip him of legal status and deport him solely on the basis of his “past, current, or expected beliefs, statements, or associations that are otherwise lawful,” according to The Associated Press.

Whether ICE actually plans to follow through on its social media post and screen for “illegal” ideas remains to be seen. But one thing can be assured, those challenging the administration’s efforts to strip students, professors and other visitors of their visas or legal status for the ideas they hold are sure to point to this social media post as evidence as they challenge the Trump administration’s assault on the First Amendment in court.