LaRose is "one of only a few such cases nationwide in which females have been charged with terrorism violations," said U.S. Department of Justice spokesman Dean Boyd.

LaRose, 46, of Pennsburg but with close ties to south Texas, has been held without bail since her Oct. 15 arrest in Philadelphia. She will be arraigned in Philadelphia on March 18.

Authorities said the case shows how terrorist groups are looking to recruit Americans to carry out their goals.

"Today's indictment, which alleges that a woman from suburban America agreed to carry out murder overseas and to provide material support to terrorists, underscores the evolving nature of the threat we face," said David Kris, assistant attorney general for national security.

LaRose had targeted Swedish artist Lars Vilks and had online discussions about her plans with at least one of several suspects apprehended over that plot Tuesday in Ireland, according to a U.S. official speaking on condition of anonymity because the official wasn't authorized to discuss details of the investigation.

Irish police said Wednesday those arrested were two Algerians, two Libyans, a Palestinian, a Croatian and an American woman married to one of the Algerian suspects. They were not identified by name.

A U.S. Department of Justice spokesman wouldn't confirm the case is related to Vilks, who angered Muslims by depicting the Prophet Muhammad with the body of a dog. At least three Swedish newspapers published the cartoon Wednesday, arguing that it had news value or was a free-speech symbol.

The indictment charges that LaRose, who also used the name Fatima LaRose online, agreed to try killing the target on orders from the unnamed terrorists she met online, and traveled to Europe in August to do so.

LaRose indicated in her online conversations that she thought her blond hair and blue eyes would help her move freely in Sweden to carry out the attack, the indictment said.

LaRose is a convert to Islam who actively recruited others, including at least one unidentified American, and her online messages expressed her willingness to become a martyr and her impatience to take action, according to the indictment and the U.S. official.

Killing the target would be her goal "till I achieve it or die trying," she wrote a south Asian suspect in March 2009, according to the indictment. Her federal public defender, Mark T. Wilson, declined to comment Tuesday.

"I'm glad she didn't kill me," Vilks told The Associated Press on Wednesday, saying the suspects appeared to be "low-tech." He said he he has built defense systems in his home to thwart would-be terrorists, including a safe room and electrified barbed wire.

U.S. Attorney Michael Levy said the indictment doesn't link LaRose to any organized terror groups.

In recent years, the only other women charged in the U.S. with terror violations were lawyer Lynne Stewart, convicted of helping imprisoned blind Sheik Omar Abdel Rahman communicate with his followers, and Aafia Siddiqui, a Pakistani scientist found guilty of shooting at U.S. personnel in Afghanistan while yelling, "Death to Americans!"

But neither case involved the kind of plotting attributed to LaRose — a woman charged with trying to foment a terror conspiracy to kill someone overseas.

Stewart has insisted she is "not a traitor," while Siddiqui has accused U.S. authorities of lying about her.

LaRose called herself JihadJane in a YouTube video in which she said she was "desperate to do something somehow to help" ease the suffering of Muslims, the indictment said. According to the 11-page document, she agreed to obtain residency in a European country and marry one of the terrorists to enable him to live there.

She moved to Europe in August with her boyfriend's stolen passport and intended to give it to one of her "brothers," the indictment said. She hoped to "live and train with jihadists and to find and kill" the targeted artist, it said.

LaRose also agreed to provide financial help to her coconspirators in Asia and Europe, the indictment charged.

LaRose had an initial court appearance on Oct. 16 but didn't enter a plea. No further court dates have been set.

Her boyfriend, Kurt Gorman, told the Philadelphia Daily News that the two met in Ennis, Texas, several years ago and that nothing seemed amiss until she packed up her clothes and moved out of their apartment in Pennsburg without warning in August, the day after his father's funeral.

"I was upset, worried. Maybe something happened to her," he said.

A few weeks later, two FBI agents visited him, and in November or December he was subpoenaed by a federal grand jury to testify, Gorman said.

"She never talked about international events, about Muslims, anything," he told the newspaper. "It's very strange. I still can't believe it."