CA : Illegal detention of US legal permanent resident Mahmoud Khalil, student activist. How can we help him?

I participated in the airport protests the last time the Trump administration tried to violate the rights of green card holders by refusing them entry into the US. My father is a green card holder. This is bullshit. How can we help Mahmoud Khalil? Where can we protest?

https://www.nytimes.com/2025/03/09/nyregion/ice-arrests-palestinian-activist-columbia-protests.html?unlocked_article_code=1.204.Gz8O.n3JAwRxrzYZv&smid=nytcore-ios-share&referringSource=articleShare