WASHINGTON (NEXSTAR) — In an unusual joint announcement, the United States and key allies are blaming China for a massive cyberattack against Microsoft Exchange last March.

The attack locked up the data of hundreds of thousands of organizations around the globe.

On Monday, President Joe Biden told reporters that unlike similar ransomware attacks by Russia-based hackers, U.S. intelligence agencies believe the Chinese government may be directly involved in the Microsoft hack.

“They’re still determining exactly what happened,” Biden said. “It may be even accommodating them being able to do it.”

The president says he’ll get a complete briefing on Tuesday and at this point, the White House is holding off on countermeasures or sanctions.

White House Press Secretary Jen Psaki says if the U.S. does take action, it will likely be together with allied countries.

“It’s a stronger way to approach malicious activity,” Psaki said.

The U.S. Department of Justice last week launched a new website to help private companies avoid ransomware attacks.

Randy Marchany, an information security expert at Virginia Tech, says it’s a good first step.

“Rasomware is not new. It’s been around since 1989,” Marchany said.

He says the hackers are simply in this for the money.

“If there’s no money or if there’s not enough money in this, then that reduces the number of attacks,” Marchany said. “This is a big cash cow.”

He says companies should encrypt and back up their data, so hackers can’t hold the data hostage.