By Jonathan Allen

NEWARK, New Jersey (Reuters) -Mahmoud Khalil vowed to resume his pro-Palestinian activism as he returned to New York a day after he was released on bail from a jail for immigrants, even as U.S. President Donald Trump's administration said it will continue its efforts to deport the recent Columbia University graduate.

He arrived at Newark Liberty International Airport in New Jersey on Saturday afternoon to cheers and ululations from friends and supporters. Khalil, 30, was reunited with his wife, a U.S. citizen, and greeted at the airport by U.S. Representative Alexandria Ocasio-Cortez, a Democrat from New York.

"Not only if they threaten me with detention, even if they would kill me, I would still speak up for Palestine again," Khalil said, holding a bouquet of flowers. "I just want to go back and just continue the work that I was already doing, advocating for Palestinian rights, speech that should actually be celebrated rather than punished."

Khalil, who recently graduated from Columbia University in Manhattan, was a prominent figure in the pro-Palestinian and anti-Israel student protest movement that swept campuses last year. Federal immigration agents arrested him in the lobby of his Columbia apartment building on March 8, making him the first target of  Trump's effort to deport international students with pro-Palestinian or anti-Israel views. 

Ocasio-Cortez, speaking alongside Khalil at the airport, condemned the Trump administration for what she called "persecution based on political speech."

"Being taken is wrong. It is illegal," she said. "It is an affront to every American."

"Free Palestine!" Khalil said with a raised fist as he left the airport.

Khalil was born and raised in a Palestinian refugee camp in Syria and became a U.S. lawful permanent resident last year. Nonetheless, citing an obscure part of federal immigration law that has not been invoked in more than 20 years, U.S. Secretary of State Marco Rubio said he had determined that Khalil and several other foreign pro-Palestinian students at U.S. schools must be deported because their presence here could harm the government's foreign policy interests.

Protesters, including some Jewish groups, say the government wrongly conflates their criticism of the Israeli government, one of the United States' closest allies, with antisemitism.

Earlier this month, U.S. District Judge Michael Farbiarz in New Jersey ruled that the government could not detain or deport Khalil based on Rubio's determination, finding the Trump administration was violating Khalil's constitutional right to free speech.

On Friday, he ordered the Trump administration to release Khalil on bail while he continues to fight the government's deportation efforts and his lawsuit accusing the government of wrongful detention.

A spokesperson for Trump said in a statement after the ruling that Khalil should be deported for "conduct detrimental to American foreign policy interests" and for omitting or incorrectly describing his employment history on his application for form to become a permanent resident. Khalil has said his application form was correct and the allegations of omission are spurious.

Also on Friday, an immigration court in Louisiana ruled that Khalil must be deported. He will now challenge the decision in the immigration court, which is run by the Department of Justice rather than the government's judicial branch, through the Board of Immigration Appeals. The Trump administration appealed Farbiarz's rulings on Friday evening to the U.S  Court of Appeals for the Third Circuit.

(Reporting by Jonathan Allen in Newark, New Jersey; Writing by Jasper Ward and Jonathan Allen;Editing by Mary Milliken and Franklin Paul)