Top law enforcement officials on Monday took shots at Apple during a press conference about last month’s shooting on a Pensacola, Florida, naval base, which they described as an act of terrorism.

Attorney General William Barr and FBI Deputy Director David Bowdich pressured the tech giant to unlock two iPhones belonging to Mohammed Saeed Alshamrani. The Saudi Arabian military trainee opened fire, killing three and injuring eight at the Naval Air Station Pensacola in December. He was part of an international training program in which Saudi military trainees studied alongside American aviation students, and his reported Twitter account indicated a possible affinity for several religious extremist figures.

Alshamrani reportedly had two iPhones. Apple has historically declined to unlock devices for law enforcement, citing user privacy.

“We have asked Apple for their help in unlocking the shooter’s iPhones,” Barr said on Monday. “So far Apple has not given us any substantive assistance. This situation perfectly illustrates why it is critical that investigators be able to get access to digital evidence once they have obtained a court order based on probable cause. We call on Apple and other technology companies to help us find a solution so that we can better protect the lives of Americans and prevent future attacks.”

When asked whether investigators had exhausted all internal options for unlocking the phone, Barr said that law enforcement doesn't “want to get into a world where we have to spend months and even years exhausting efforts when lives are in the balance.”

Apple disputed Barr's description of their talks. "We reject the characterization that Apple has not provided substantive assistance in the Pensacola investigation. Our responses to their many requests since the attack have been timely, thorough and are ongoing," the company told The Daily Beast in a statement, adding that it had turned over some requested information like iCloud backups and transaction data.

But the company pushed back on requests to decrypt the phone or build a "backdoor" through which law enforcement could have special access to Apple devices.

"We have always maintained there is no such thing as a backdoor just for the good guys," the company wrote. "Backdoors can also be exploited by those who threaten our national security and the data security of our customers. Today, law enforcement has access to more data than ever before in history, so Americans do not have to choose between weakening encryption and solving investigations. We feel strongly encryption is vital to protecting our country and our users' data."

The FBI and Apple have previously squared off over the tech company’s refusal to unlock devices. After a 2015 mass shooting in San Bernardino, California, the law enforcement agency claimed it was unable to unlock the shooter’s phone, and called on Apple to open it for investigation. Amid a protracted legal battle, the FBI hired the Israeli firm Cellebrite to crack into the phone, instead. The move prompted backlash from privacy advocates like the Electronic Frontier Foundation, which claimed it was evidence that the FBI always had the ability to crack the phones, but that it had mounted a pressure campaign against Apple to establish a backdoor that law enforcement could use in future searches.

Alshamrani, a second lieutenant in the Saudi Air Force, was said to engage in behavior before the shooting that has since cast scrutiny on his fellow Saudi classmates at the Florida air base. In the days prior, he allegedly hosted a dinner party where he screened footage of mass shootings. But contrary to initial reports, law enforcement said Monday that Saudi students had not filmed the shooting in connection with Alshamrani, and instead had begun filming when they found themselves unwittingly near the attendant commotion.

Still, more than a dozen of Alshamrani’s Saudi classmates will be expelled, CNN reported Saturday, although none have been accused of aiding in the shooting. Some are accused of possessing child pornography, while others are accused of having their own connections to extremist movements, according to an official who spoke to The New York Times. Approximately 850 Saudi students, nationally, take part in military training programs in the U.S.

The military was reportedly reviewing its vetting procedures for foreign military students after the shooting.

Alshamrani might have been radicalized in an extreme ideology even before he came to the U.S., according to a report by the Saudi government that was reviewed by The Washington Post. According to the report, he may have begun sharing “tweets and retweets [that] demonstrate his radicalization” in 2015. He reportedly followed multiple radical Muslim figures on Twitter, including some that encouraged violence toward America. One of several tweets reviewed by the SITE intelligence group before the account was deleted quoted former al-Qaeda leader Osama Bin Laden. Shortly before the shooting, Alshamrani appears to have shared a message calling the U.S. a “nation of evil.”

He also appeared to begin the process of buying the gun he used in the shooting months earlier, in April 2019. “He’d been thinking about this for a long time it looks like,” a senior law enforcement official previously told The Daily Beast. He also visited the 9/11 Memorial and Museum in New York City in the weeks before the shooting.

This article has been updated with comment from Apple.