8 USC 1182
and 8 USC 1227
This has been this way since 2005 and worst, has been used this way in the past. Note that no “material” support of terrorism needs to be alleged and no formal crime must be committed. Mere speech suffices. No due process, only "reasonable ground to believe, is engaged in or is likely to engage after entry".
As someone who works with international students on a daily basis, this is why I caution them all to not get involved in things like this. There is a much different set of rules for a green card holder or being on a student visa and being a citizen. It is not very difficult to come up with "a consular officer, the Attorney General, or the Secretary of Homeland Security knows, or has reasonable ground to believe, is engaged in or is likely to engage after entry in any terrorist activity" as defined as "(VII) endorses or espouses terrorist activity or persuades others to endorse or espouse terrorist activity or support a terrorist organization"