The US Department of Justice has concluded that a fatal shooting at a naval base in Florida last month was an act of terrorism by a Saudi Arabian military trainee.
Investigators didn't find evidence that other members of the Saudi military or any foreign nationals in the USA assisted in the Pensacola attack or had advance knowledge of it, Barr said.
"However, the kingdom of Saudi Arabia determined that this material demonstrated conduct unbecoming an officer in the Royal Saudi Air Force and in the Royal Navy", Barr said, adding that "the 21 cadets have been disenrolled from their training curriculum in the United States military and will be returning to Saudi Arabia later today".
Quoting unnamed sources, CNN reported Saudi personnel being expelled are not accused of aiding the Saudi Air Force second lieutenant who killed three American sailors at the Pensacola installation. Alshamrani was killed during the attack.
"The consensus was reached, after all efforts to access the shooter's phones had been unsuccessful, that the next step was to reach out to start a conversation with Apple".
In a statement Tuesday night, the American Civil Liberties Union said the Trump administration's request of Apple was "dangerous and unconstitutional, and would weaken the security of millions of iPhones".
Mr Barr described the shooting at Naval Air Station Pensacola as an "act of terrorism".
Last week, Apple said it had already provided all the information in its possession to the Federal Bureau of Investigation.
"This situation perfectly illustrates why it is critical that the public be able to get access to digital evidence", Mr. Barr said.
Still, US government officials, including Trump's Attorney General William Barr, have complained that Apple isn't doing enough to help unlock the iPhones of the Florida attacker.
"We reject the characterisation that Apple has not provided substantive assistance in the Pensacola investigation".
We have asked Apple for its help in unlocking the shooter's phones.
Investigators have been trying to access the two devices - an iPhone 7 and an iPhone 5 - but have been unable to access them because the phones are locked and encrypted, according to a letter from the FBI's general counsel, Dana Boente.