Al-Qaeda kingpin Osama bin Laden's son-in-law has been detained by US authorities and is due to appear in court in New York on Friday on terrorism charges, the Justice Department said.
Sulaiman Abu Ghaith, reportedly a 47-year-old Kuwaiti and allegedly one of the chief propagandists of the al-Qaeda network, stands accused of conspiring "to kill nationals of the United States," the department said.
Attorney General Eric Holder said the arrest showed that the United States would never relent in its pursuit of the militants who launched the attacks of 11 September 2001 on New York and Washington.
"No amount of distance or time will weaken our resolve to bring America's enemies to justice," Holder said.
"To violent extremists who threaten the American people and seek to undermine our way of life, this arrest sends an unmistakable message," he said.
"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, the al-Qaeda chief who was gunned down 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.
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".
A Turkish newspaper had reported earlier that Ghaith was seized by US authorities at a hotel in Ankara last month and was deported to Jordan, before being taken to the United States.