A federal judge Tuesday continued the imprisonment of four Twin Cities men arrested in April who authorities say are part of a larger conspiracy to travel to Syria to join the Islamic State of Iraq and the Levant, while leaving open the possibility of later releasing them to "less restrictive conditions."

U.S. District Judge Michael Davis affirmed a magistrate judge's earlier decision to imprison the men while they await trial on federal charges of plotting to join ISIL, a State Department-designated terror group.

While contending that their release would pose too great a risk to the community, Davis said he would consider alternatives to detention for four of the defendants who appeared in court on Tuesday morning: Adnan Farah, 19, and Hanad Musse, 19, Zacharia Abdurahman, 19, and Guled Omar, 20.

"The court is open to hearing about a plan to deal with the issues that we have here, about flight. It is open to hearing about a plan to dealing with the safety of the community," Davis said at the hearing. "Each individual is different. There is no cookie-cutter plan."

He added that the case of Abdullahi Yusuf, another alleged recruit who was arrested this week for allegedly violating conditions after Davis sent him to halfway house instead of prison, had no bearing on his ruling.

The appeal of a detention order for another man, 20-year-old Hamza Ahmed, who along with three of the defendants was detained by federal authorities while trying to leave the country last fall and later indicted, also was denied. Davis said he also would consider a less restrictive detention for Ahmed, whose case is expected to be lumped in with the others. He made his first appearance Tuesday alongside the other defendants.

After Omar's attorney raised concerns about his client's imprisonment at the Ramsey County jail, where he was under 22-hour-a-day solitary confinement, Davis ordered him transferred.

"I want you to know that I will take a look at the possibility of release to less restrictive conditions," the judge told Omar's parents.

On Tuesday, roughly 120 family members and supporters crammed into the courtroom to follow the proceedings.

The scene was less tense than at a detention hearing in St. Paul last month, although security remained tight.

The ruling comes amid heightened interdiction efforts in the Twin Cities, which authorities say remains a fertile recruiting ground for Islamic extremism.

If a federal grand jury returns indictments against the defendants, they could be charged with conspiring to provide material support to a foreign terrorist organization, which carries a maximum sentence of 15 years in prison.