Muhanad Badawi and Nader Elhuzayel, both 24, were arrested late Thursday by special agents with the FBI -- Elhuzayel at Los Angeles International Airport and Badawi at an apartment in Anaheim, officials said.
There was never any local public safety threat and both were apprehended unarmed, according to the FBI.
The FBI, in connection with a joint terrorism task force, also served at least two search warrants in connection with the case.
An affidavit in support of a criminal complaint, filed Friday in Santa Ana federal court, outlines an alleged scheme in which Badawi and Elhuzayel used social media to discuss ISIS and terrorist attacks, expressed a desire to die as martyrs and made arrangements for Elhuzayel to leave the United States to join ISIS, according to the U.S. Attorney's Office.
According to the affidavit, on May 3, Elhuzayel saw a Twitter post from Elton Simpson, one of the two gunmen who were killed trying to attack a conference in Garland, Texas. In the tweet, Simpson stated that he and his "bro'' had pledged allegiance to the leader of ISIS, prosecutors said.
In response, Elhuzayel tweeted his support for the attempted attack and praised Simpson as a ``martyr,'' according to federal prosecutors.
In recorded conversations last month, Badawi and Elhuzayel "discussed how it would be a blessing to fight for the cause of Allah, and to die in the battlefield,'' and they referred to ISIS as "we,'' according to the affidavit.
Prosecutors allege that when Badawi expressed concerns about ISIS struggling due to airstrikes by coalition forces, Elhuzayel responded that they had to be patient, and "can you imagine when al-Qaida joins with Islamic State''?
According to the affidavit, Badawi responded: "We will be huge.''
The two men also discussed local Muslim leaders, with Elhuzayel complaining that these leaders were not "legitimate'' because they believed in democracy and were not fighting for an Islamic State, prosecutors contend.
The men discussed where in the Middle East they would rather be, and Elhuzayel said he wanted to fight and did not want to be in the United States, according to the conversations recounted in the affidavit.
On May 7, Badawi allowed Elhuzayel to use his credit card to purchase a one-way airline ticket for travel from Los Angeles to Tel Aviv, Israel, via Istanbul, Turkey, on a Turkish Airlines flight scheduled to depart Thursday, according to the U.S. Attorney's Office.
Badawi indicated that he would be traveling to the Middle East in the future, according to the affidavit.
According to the allegations in the complaint, Elhuzayel admitted after being read his Miranda rights that he planned to disembark in Istanbul to join ISIS and did not intend to travel on to Israel.
If convicted of the charge in the criminal complaint, Badawi and Elhuzayel each would face up to 15 years in federal prison for conspiring to provide material support to ISIS, prosecutors noted.
Elhuzayel's parents said their son was traveling to spend the summer with relatives, not to join a terrorist group.
"Completely beyond any sensible thoughts,'' his father, Salem Elhuzayel, told news outlets. "He is not the type. He is a good kid.''
His mother, Falak Elhuzayel, said the FBI kicked in the door of their room at the Crystal Inn motel, 2123 W. Lincoln Ave. in Anaheim, and ransacked it.
"They stole my computers from the car,'' she told news outlets. "They took my checkbooks, my credit cards, everything was gone.''
Elhuzayel's parents said their son and Badawi were classmates together at Cypress College.
The Muslim Public Affairs Council issued a statement saying the arrests were based on the two suspects' social media comments, in which they expressed support for ISIS. Both men had purchased plane tickets, with Elhuzayel bound for Turkey, according to MPAC.
"ISIS uses social media to prey on impressionable people,'' according to MPAC. "According to law enforcement, ISIS puts out close to 100,000 tweets per day and there are at least 50,000 ISIS-related Twitter accounts.''
The group said it is "working to bridge the relationship between law enforcement and communities to ensure that communities are safe and are treated as partners rather than suspects.''