Federal prosecutors have filed fresh, tougher charges against five Twin Cities men who were accused earlier this year of plotting to leave the U.S. to join the Islamic State in Iraq and the Levant.

A broader, "superseding indictment" was filed Wednesday afternoon in U.S. District Court after a federal grand jury decided that the government had presented enough evidence to bring additional charges against some or all of the defendants, including perjury, financial aid fraud and conspiracy to commit murder abroad. The latter charge, which often has been used against suspected jihadists, carries a maximum sentence of life in prison.

All five men — Guled Omar, Hamza Ahmed, brothers Adnan and Mohamed Farah, and Abdirahman Daud — remained jailed pending trial, which is slated for February.

Several attorneys for the defendants said privately that the new charges were a thinly veiled attempt to pressure their clients into pleading guilty. The families of the five men said they have rejected plea agreements offered by prosecutors in recent months.

Speaking by phone Wednesday night, Daud's attorney Bruce Nestor said the new charges "upped the ante from the government. This carries a life sentence for these young men who haven't been accused of harming anyone, only allegedly talking about harming someone."

On Wednesday, Ben Petok, a spokesman with the U.S. attorney's office, declined to comment on recent charges, citing the unresolved federal case.

"It's an ongoing investigation and we presented appropriate charges to the grand jury based on the available evidence, and this second superseding indictment is the result of that," Petok said.

Sadik Warfa, a community leader who has been a spokesman for several of the defendants' families, said they believe the new indictment is "part of a government pressure to get some of the young men to take a deal."

Prosecutors contend that the men were part of a broader conspiracy, dating to the spring of last year, which sought to aid ISIL in its fight to establish an Islamic-run state, or caliphate. Several young Twin Cities men, friends of the alleged conspirators, successfully left the country and joined ISIL fighters in Syria and Iraq, authorities said.

When asked about their ties to the departed fighters, some of the defendants repeatedly lied to a federal grand jury, according to authorities.

Two others, Zacharia Abdurahman and Hanad Musse, pleaded guilty in September to conspiracy to provide material support to a terrorist organization. Another defendant, Abdullahi Yusuf, pleaded guilty to conspiracy in February and turned state's witness. All three men await sentencing.

Law enforcement officials have said that extremist groups like ISIL and Al-Shabab continue to recruit young people, urging them to leave the West and join their cause.

Authorities first hinted at the possibility of new charges in a federal search warrant application filed in September that sought access to Omar's social media accounts.

The warrant showed that, in addition to his public Twitter account, Omar maintained a "dirty jihadi" account that he hid from all but his closest friends and used to communicate with ISIL sympathizers from around the world.

In the filing, authorities argued that Omar — whose older brother was one of at least 22 men who left Minnesota nearly a decade ago to join Al-Shabab — tried to join Al-Qaida's branch in Somalia in August 2012, but was prevented from boarding a flight to Kenya. At the time, Omar told customs agents that he was traveling to attend an uncle's wedding, then later told the FBI that he was going to get married in Africa, according to court documents.

Attorney JaneAnne Murray, who represents Hamza Ahmed, said there "is no evidence that any of these defendants … acted with the aim or intent of committing murder." She declined further comment.

More than 250 Americans have tried to reach or reached Syria and Iraq to fight with terrorist groups, according to intelligence estimates. Roughly a dozen Minnesotans have joined extremist groups in the Middle East.

But federal officials say that the flow of jihadi recruits from the U.S. has slowed over the past few months.

FBI Director James Comey, at a congressional hearing on Wednesday, attributed some of the drop to improved interdiction efforts by U.S. law enforcement agencies.