Osama bin Laden's son-in-law has pleaded not guilty at a court in New York to charges of conspiring to kill US nationals.
Suleiman Abu Ghaith, reportedly a 47-year-old Kuwaiti and allegedly one of the chief propagandists of the al-Qaeda network, entered the plea through a lawyer on Friday.
Abu Ghaith, who was brought to the US after being arrested in Jordan, stands accused of plotting "to kill nationals of the United States", the US Justice Department said on Thursday.
Eric Holder, US attorney-general, said the arrest showed that the US would never relent in its pursuit of the fighters who launched the attacks of September 11, 2001, on New York and Washington.
"No amount of distance or time will weaken our resolve to bring America's enemies to justice," he said.
"To violent extremists who threaten the American people and seek to undermine our way of life, this arrest sends an unmistakable message.
"There is no corner of the world where you can escape from justice because we will do everything in our power to hold you accountable to the fullest extent of the law."
US authorities accuse Ghaith of assisting bin Laden, who was killed in a 2011 raid by American commandos, and of taking to the airwaves to promote al-Qaeda's war against America after the 9/11 attacks.
'Great army gathering'
According to the indictment he allegedly threatened Americans, warning them that a "great army is gathering" and "the storms shall not stop, especially the airplanes storm".
Exactly how the US captured Abu Ghaith is still unclear.
Peter King, the former Republican chairman of the House Homeland Security Committee, credited the CIA and FBI with catching him in Jordan within the last week.
A Jordanian security official confirmed that Abu Ghaith was handed over last week to US law enforcement officials under both nations' extradition treaty. He declined to disclose other details and spoke on condition of anonymity because of the sensitivity of the matter.
The Turkish newspaper Hurriyet reported that Abu Ghaith was caught on his way to Kuwait, shortly after leaving Turkey.
The newspaper said that Abu Ghaith was taken into custody more than a month ago at a luxury hotel in in Ankara, the Turkish capital. But Turkish officials decided he had not committed any crime in Turkey and released him, Hurriyet reported.
King called the arrest a "very significant victory" in the ongoing fight against al-Qaeda.
He said the capture was confirmed to him by US law enforcement officials.