President Joe Biden said “we’re not sure” that Russia is behind a massive ransomware attack on managed-service providers as U.S. intelligence officials conduct an investigation.

“I directed the full resources of the government to assist in the response if needed,” Biden told reporters during a trip to Michigan on Saturday.

“We’re not sure it’s the Russians,” Biden said. “I got a brief on the plane. The initial thinking was, it was not Russian government, but we’re not sure yet.”

The timing of the attack is sensitive, just weeks after Biden implored Russian President Vladimir Putin to curb cyber crime.

“I directed the intelligence community to give me a deep dive on what’s happened,” Biden said. “I’ll know better tomorrow and if it is either with the knowledge of and/or a consequence of Russia, then I told Putin we will respond.” He said he hadn’t spoken to the Russian president about the latest case.

A Republican National Committee spokesman said the group was alerted by Microsoft Corp. that Synnex Corp., one of the RNC’s vendors, “may have been exposed.”

“There is no indication the RNC was hacked or any RNC information was stolen. We are investigating the matter and have informed DHS and the FBI,” spokesman Mike Reed said by email.

REvil, a Russia-linked group blamed for the May 30 ransomware attack of meatpacking giant JBS SA, is believed to be behind the hacks on at least 20 managed-service providers, which provide IT services to small- and medium-sized businesses.

More than 1,000 businesses are affected and the number is expected to increase, according to the cybersecurity firm Huntress Labs Inc.

(Updates with RNC statement in seventh paragraph.)

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