Investigators do not know yet whether encryption helped the Brussels attackers hide from authorities, Attorney General Loretta Lynch told reporters Thursday.
The terrorists killed more than 30 people in a coordinated strike Tuesday that featured mulitple blasts across the city.
It will be up to Brussels authorities, she added, to reveal any details regarding the attackers’ use of encryption.
Brussels was rocked by three explosions Tuesday — two at Zaventem airport and another at a metro station near European Union buildings. The Islamic State in Iraq and Syria (ISIS) has claimed credit for the plot.
Lynch’s remarks on encryption echo the sentiments thus far from top intelligence and homeland security lawmakers on Capitol Hill.
“We don’t know yet,” House Intelligence Committee Chairman Devin Nunes (R-Calif.) told reporters Wednesday.
Still, many have assumed encryption was involved in some capacity.
“I’m sure that that’s the case,” Nunes added, “because that’s what they’re all doing.”
The deadly assault is the third major terror attack in a Western country in recent months, following the assault in Paris that left 130 people dead and the shootings in San Bernardino, Calif., that killed 14 people.
Lawmakers and investigators say authorities are increasingly blind to these plots because of extremists’ use of encryption. The FBI and law enforcement have pushed for guaranteed access to secure data in response.
But technologists argue that encryption is an important security measure for everyday users of the Internet. They say ensuring access to secure data weakens global security and endangers online privacy.
The growing number of terror attacks has raised pressure on Congress to settle the contentious debate by defining when authorities should be able to get at encrypted information.
A bill from Sens. Richard BurrRichard BurrA guide to the committees: Senate Juan Williams: Senate GOP begins to push Trump away Report: Senate Intel Committee asks agencies to keep records related to Russian probe MORE (R-N.C.) and Dianne FeinsteinDianne FeinsteinA guide to the committees: Senate Dem: Trump's China trademark looks like a quid pro quo Senate advances Trump's Commerce pick MORE (D-Calif.) — the leaders of the Senate Intelligence Committee — would force companies to decrypt data upon government request.
Another measure, from House Homeland Security Committee Chairman Michael McCaul (R-Texas) and Sen. Mark WarnerMark WarnerA guide to the committees: Senate Report: Senate Intel Committee asks agencies to keep records related to Russian probe Comey meets Intel senators amid uproar over Trump-Russia ties MORE (D-Va.), would create a national commission to study the issue first, before deciding on any policy changes.
Two House committees on Monday also established a congressional encryption working group to look into possible solutions.
McCaul on Tuesday told reporters that future ISIS attacks would “no doubt involve encryption,” making it urgent that Congress act.
“It’s important that Congress does something,” he said.