U.S. Magistrate Judge William Webb said the defendants have contacts in foreign countries and either have access to large amounts of money or were able to raise it. The judge also said the penalties they face if convicted make them liable to leave the country.
"A potential life sentence in and of itself constitutes a risk of flight," Webb said.
Alleged ringleader Daniel Patrick Boyd, 39, and six other men, including two of Boyd's sons, were charged last week with plotting to murder, kidnap, maim and injure persons in an unspecified foreign country. An eighth man is being sought.
On the first day of the detention hearing Tuesday, and talking about the struggle of Muslims, the honor of martyrdom and his disgust at the U.S. military.
A seventh suspect in the case requested a new interpreter and attorney, so his detention hearing was delayed.
Prosecutors had argued earlier Wednesday that the men were a flight risk, noting aspirations for jihad, some past encounters with the law and plans to travel overseas.
Defense attorneys countered that the men had strong ties to their communities and that at least some were not followers of Boyd.
As U.S. marshals led the men away following Webb's ruling, the suspects said the same phrase they had uttered in court a day earlier: "May peace be upon you," they said in Arabic.
"May peace be upon you, also," many audience members murmured in response.
"I just want to say that we appreciate the support of the whole community and that we love our families very much," Daniel Boyd's wife Sabrina Boyd said outside the courtroom, her voice wavering. "We're just trying to be patient."
On Tuesday, federal investigators told the judge they seized from Boyd's home and cars more than 27,400 rounds of ammunition, 26 weapons, gas masks, a handbook on how authorities respond to acts of terrorism and the text of a fatwa urging jihad against Americans. One agent testified that a trench dug under Boyd's deck was described by a witness as a place to hide weapons.
FBI Special Agent Michael Sutton testified Tuesday that Boyd recruited followers with stories of his past. Boyd told the FBI he had trained in a secret Connecticut camp before going to Pakistan and Afghanistan two decades ago to continue training there.
Boyd's two sons 20-year-old Zakariya and 22-year-old Dylan have also been indicted. The other suspected group members are Anes Subasic, 33; Mohammad Omar Aly Hassan, 22; Ziyad Yaghi, 21; and Hysen Sherifi, 24.
Webb ordered that Subasic's hearing be held later because he requested a new attorney and interpreter. An eighth man, Jude Kenan Mohammad, is still at large and Sutton said Tuesday authorities last heard he was in Pakistan.