A U.S. judge has ruled that the Trump administration can proceed with the deportation of Mahmoud Khalil, a Columbia University graduate who was detained last month for his involvement in pro-Palestinian demonstrations.Khalil, a lawful permanent resident of the U.S., has not been formally charged with any crime. In a letter written from the detention facility, he claimed that his arrest was a direct result of his advocacy for Palestinian rights.Authorities are relying on a Cold War-era immigration statute, arguing that his continued presence in the U.S. conflicts with the country’s foreign policy interests.Khalil has been held in a detention center in Louisiana since March 8, when immigration officials informed him he was being deported for participating in protests opposing the war in Gaza.