The men allegedly traveled to remote desert areas near Phoenix for target practice during the first half of 2015, according to the indictment, which also accuses Kareem of transporting firearms and ammunition across state lines.

Kareem allegedly feigned having been struck by a car and attempted to make an insurance claim based in his injuries in order to raise money for attacks, the indictment said.

In addition to providing arms to Simpson and Soofi, Kareem hosted the two men and others at his home to discuss the attack on the cartoon contest, the court documents said.

For months, the trio and other men watched videos "depicting jihadist violence and apparent wartime footage in Syria, Iraq and elsewhere in the Middle East" as well "torture and executions" by ISIS members, according to the indictment.

"While watching the videos, Kareem exhorted and encouraged Simpson and Soofi to engage in violent activity in the United States to support [ISIS] and impose retribution for United States military actions in the Middle East," the indictment said.

From December to May 2014, Kareem and others allegedly attempted to acquire pipe bombs and inquired about what type of explosives would be needed to create maximum damage at venues such as the mall at Westgate and nearby University of Phoenix Stadium, where the Super Bowl was to be played on February 1, the indictment said.

On March 20, Simpson, according to the indictment, accessed an ISIS list of the home addresses of U.S. military personnel. A handwritten note found later in an apartment shared by Simpson and Sofi had the name and address of an Arizona service member targeted by ISIS. Simpson, Soofi and others also scouted military installations for planned attacks, the indictment alleged.

Kareem was charged on Wednesday with conspiracy to provide material support to a foreign terrorist organization, interstate transportation of firearms with intent to commit a felony, making false statements and other crimes. An indictment earlier this year charged him with conspiracy and weapons charges in connection with the attack in Garland.

Kareem's attorney could not be reached for comment.

Kareem was detained in Phoenix last June. The city is home to the Islamic Community Center of Phoenix, which Simpson, Soofi and Kareem attended for a time. Kareem also cleaned carpets at the center, its president, Usama Shami, told CNN at the time.

ISIS began taking over large swaths of Iraq and Syria in early 2014, ruthlessly imposing its will -- with widespread killings, rapes and enslaving of innocents -- on those who don't submit. Such tactics have drawn the ire of the U.S. government, which has taken a leading role in supplying Iraqi forces and conducting a military air campaign against ISIS targets.

ISIS said it was behind the Garland attack.

But ISIS members aren't the only ones who might have taken offense to the Texas event.

The Quran, Islam's holy book, does not explicitly bar portrayals of Mohammed.

But the religion has long discouraged any such images to avoid temptation toward idol worship, with many Muslims' thus finding such depictions extremely offensive.

Most express these views peacefully. But there are exceptions, such as the January attack on the Paris office of Charlie Hebdo -- a satirical magazine that drew derision for its publication of cartoons featuring Mohammed.

The Charlie Hebdo carnage, in which 12 people were killed, sparked an outcry worldwide. Authorities found an ISIS flag in the hideaway of one of the Paris gunmen, but another group, al Qaeda in the Arabian Peninsula, claimed it engineered the attack.