WASHINGTON (AP) — President Joe Biden is meeting Wednesday with top executives from some of the country's leading technology companies and financial institutions as the White House urges the private sector to help toughen cybersecurity defenses against increasingly sophisticated attacks.

The summit comes during a relentless stretch of ransomware attacks that have targeted critical infrastructure, in some cases with the attackers extorting multimillion-dollar payments from major corporations, as well as other illicit cyber operations that U.S. authorities have linked to foreign hackers.

In public remarks before the private meeting got underway, Biden referred to cybersecurity as a “core national security challenge” for the U.S.

“The reality is most of our critical infrastructure is owned and operated by the private sector, and the federal government can't meet this challenge alone,” Biden said. “I've invited you all here today because you have the power, the capacity and the responsibility, I believe, to raise the bar on cybersecurity.”

Though ransomware is one focus of Wednesday’s gathering, the purpose of the meeting is broader and centered on identifying the “root causes of malicious cyber activities” and ways in which the private sector can help bolster cybersecurity, said a senior administration official who briefed reporters on the condition of anonymity.

The guest list for Wednesday's meeting includes Apple chief executive Tim Cook, Amazon chief executive Andy Jassy and Sundar Pichai, the CEO of Alphabet Inc., Google's parent company. Also on the list are the leaders of IBM, Microsoft and Automatic Data Processing. Besides Biden, multiple Cabinet secretaries and national security officials are representing the administration.

The meeting is taking place as Biden's national security team has been consumed by the troop withdrawal in Afghanistan and the chaotic evacuation of Americans and Afghan citizens. The fact the meeting remained on the calendar underscores how the administration regards cybersecurity as a major agenda item, with a senior administration official describing Wednesday's event as a “call to action.”

Financial industry executives are also expected, including the chief executives of Bank of America and JPMorgan Chase, as well as representatives from the energy, education and insurance sectors.

The broad cross-section of participants underscores how cyber attacks have cut across virtually all sectors of commerce. In May, for instance, hackers associated with a Russia-based cyber gang launched a ransomware attack on a major fuel pipeline in the U.S., causing the company to temporarily halt operations. Weeks later, the world's largest meat processor, JBS SA, was hit with an attack by a different hacking group.

In both instances, the companies made multimillion-dollar ransom payments in an effort to get back online.

Biden on Wednesday pointed to a summit with Russian President Vladimir Putin in which he said he made clear his expectation that Russia take steps to rein in ransomware gangs because “they know where they are and who they are.”

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