PITTSBURGH (AP) — A young Syrian refugee was ordered to remain behind bars until his trial on charges he plotted to bomb a Pittsburgh church to inspire followers of the Islamic State of Iraq.

Mustafa Mousab Alowemer, 21, who came to the U.S. as a refugee in 2016, was arrested Wednesday while meeting with one of two FBI undercover operatives posing as Islamic State sympathizers.

The government said the FBI began its covert operation in March when it decided to assess if he posed a threat.

He "immediately and frequently responded with great enthusiasm," FBI agent Gary Morgan testified Friday at a hearing before a federal magistrate, who ordered Alowemer detained.

When taken into custody, Alowemer told FBI agents "he knew what he was doing was terrorist acts and knew he could be arrested," Morgan said.

"Mr. Alowemer stated he felt an inner drive to carry out the attacks," the FBI agent said.

Alowemer, wearing an orange jumpsuit, listened intently to his Arabic translator during the court hearing. As he was being taken out of the courtroom, one woman cried and a man yelled out something in Arabic.

The Pittsburgh resident is charged with attempting to provide material support to the Islamic State of Iraq and distributing information relating to an explosive device or weapon of mass destruction. Federal authorities allege he planned to bomb the Legacy International Worship Center, a small Christian church, which is about 10 miles (16 kilometers) from the Tree of Life synagogue, where a gunman killed 11 people and injured seven in October.

Alowemer told undercover agents he wanted one bomb to go off in the early morning hours of a Sunday, and another to explode about two to three hours later, when law enforcement would be responding, Morgan said.

He hoped to frighten people from attending church, Morgan said.

Alowemer has not yet entered a plea.

The FBI said Alowemer laid out his plan in detail, including providing maps of the area, routes, and bought items for the bomb, such as nail polish with acetone, ice packs, 9-volt batteries, and boxes of nails to serve as shrapnel.

But his attorney, Sam Saylor, argued items bought in drugstore or hardware stores do not imply an attempt to make a bomb. He called Alowemer a young man, and young men are "engaged in puffery, engaged in bragging."

Saylor also said no explosive device was made, found or planted, and that Alowemer never represented himself as an expert on bomb-making."

"I'm trying to get to the intent of my client here," he told the court.

Assistant U.S. Attorney Soo Song said Alowemer "is not charged because of his thought or his speech, he is charged because of his actions."

"He said how he wanted others in the United States to rise up in the name of ISIS. He gave plans to a man he knew to be a bomb maker," she said.

According to the FBI testimony, Alowemer initially proposed a Shia mosque in the Pittsburgh area as a target but changed his mind after his surveillance revealed the mosque had security cameras and was near a police station, Morgan said. Alowemer, a Sunni Muslim, also found out Sunni Muslims frequented that mosque.

The FBI said he later chose the church as a target for sometime in July because "at the time, he believed it to be a Nigerian church" and the attacks would "avenge the brothers in Nigeria," long the scene of Muslim-Christian violence.

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