IBM’s big leadership change went into effect today, with Arvind Krishna taking over the computing giant as CEO and throwing down a hybrid-cloud challenge for the organization. That challenge will rely heavily on IBM’s Red Hat business unit, which also received a new leader.

In a LinkedIn message to IBM’s employees, Krishna said he wants the company to add a greater presence in the hybrid-cloud space to its already established positions in the mainframe, services, and middleware ecosystem.

“The fundamentals are already in place,” Krishna wrote. “Our approach to hybrid cloud is the most flexible and the most cost effective for our clients in the long term. Coupled with our deep expertise, IBM has unique capabilities to help our clients realize the potential of a hybrid cloud business model.”

Krishna stated that IBM would take advantage of its already established presence in cloud, artificial intelligence (AI), blockchain, and quantum computing. He noted that two “strategic battles” were taking place in the journeys to hybrid cloud and AI.

“We all need to understand and leverage IBM’s sources of competitive advantage,” Krishna explained. “Namely, our open source and security leadership, our deep expertise and trust, and the fact that we enable clients to build mission-critical applications once and run them anywhere.”

He also noted that IBM has the assets in place to deal with the “architectural battle” in the cloud space that will rely heavily on its Red Hat assets. “There’s a unique window of opportunity for IBM and Red Hat to establish Linux, containers, and Kubernetes as the new standard. We can make Red Hat OpenShift the default choice for hybrid cloud in the same way that Red Hat Enterprise Linux is the default choice for the operating system.”

IBM was recently lauded by Forrester Research for aggressively targeting the cloud-native Kubernetes space through its $34 billion acquisition of Red Hat and focus on hybrid- and multi-cloud deployments. And while it might lack some of the in-depth tools sported by those higher on the list, IBM was cited as being a good pick for enterprises that have a lot of legacy equipment to deal with.

Synergy Research Group had IBM ranked as No. 4 in terms of worldwide market revenue share of the cloud market for the fourth quarter of last year. It’s 6% share was substantially lower than market heavyweights Amazon Web Services (AWS), Microsoft, and Google.

Krishna brings a strong cloud-focus to his new position, having most recently served as SVP for cloud and cognitive software at IBM. He was tapped earlier this year to replace Ginni Rometty, who had been CEO since 2012. Rometty’s tenure included a number of large acquisitions, including the Red Hat deal, which is the biggest in the company’s history.

“This is the moment we reset the cloud landscape, and it’s all about being the No. 1 hybrid cloud provider in the world right now,” Rometty said during an interview with CNN following the close of the Red Hat deal. “It is what clients need right now, and 80% of their workloads still need to move to the cloud.”

Krishna also today said that Bank of America CTO Howard Boville will join IBM as SVP of its cloud platform effective May 1. “He is a proven strategist and expert in the realm of cloud and has played a critical role in developing the financial services ready public cloud with IBM,” Krishna wrote of Boville.

IBM’s hybrid-cloud focus will also be powered by former Red Hat CEO Jim Whitehurst taking over as president of IBM. That move was part of the initial Krishna announcement and included at least one analyst lobbying for Whitehurst to get the CEO role.

“While no individual is singularly responsible for the stock performance of a large organization, we nevertheless think a change can help in terms of leadership at the top,” BMO Capital Markets’ Keith Bachman noted in a research report on the IBM CEO move at that time. “In particular, we are very encouraged that Jim Whitehurst will be staying on at IBM as president, although we would have liked for Jim to get the top job.”

Red Hat today announced that Paul Cormier was taking on the leadership position at the company as president. Cormier has been at Red Hat since 2001, and previously served as president of products and technologies.