Former Department of Defense cybersecurity leader brings deep cyber defense expertise as organizations navigate growing cyber risk in the Hybrid AI era
Gigamon, a leader in deep observability, today announced the appointment of Grant Yacomeni as chief information security officer (CISO), reporting to Chief Operating Officer Gareth Maclachlan. Yacomeni will lead information and product security, cybersecurity and IT operations, and governance, risk, and compliance (GRC), strengthening the Gigamon security strategy while bringing a seasoned practitioner perspective to customers navigating growing cyber risk and operational complexity in the Hybrid AI era.
The appointment comes as AI adoption reshapes both hybrid cloud infrastructure and the threat landscape. As organizations embed AI across applications, workflows, and business processes, new connections among models, applications, infrastructure, and sensitive data are expanding both opportunity and cyber risk. According to the 2026 Hybrid Cloud Security Survey of more than 1,000 security and IT leaders, 33 percent reported that their AI/LLM systems were targeted in breaches over the past year.
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Deep Cybersecurity and National Security Expertise
Yacomeni brings more than a decade of cybersecurity and national security experience to Gigamon. Prior to joining the company, he held leadership roles within the United States Intelligence Community (IC), including the Department of Defense (DoD), where he led enterprise security programs and 24×7 defensive cyber operations. He previously served in intelligence and cybersecurity roles with the Maryland Army National Guard and is a U.S. Marine Corps veteran.
As CISO at Gigamon, Yacomeni will focus on managing cyber risk while enabling the business to innovate and operate securely. He will engage with customers and industry leaders as organizations evolve security strategies for hybrid cloud infrastructure increasingly shaped by AI.
“Grant has spent his career operating in some of the world’s most demanding cybersecurity environments,” said Maclachlan. “His experience will be invaluable as we strengthen security across Gigamon and bring an even deeper practitioner perspective to our customers. As AI becomes increasingly embedded across hybrid cloud infrastructure, security, resilience, and business risk are becoming more interconnected. Grant is an outstanding addition to our leadership team at exactly the right time.”
Security leaders increasingly need visibility into how AI models and agents interact with applications and data, what actions they take, and whether the intelligence driving those actions can be trusted.
“AI raises the stakes for security leaders because it can act on information at a speed and scale we haven’t faced before,” said Yacomeni. “Security teams need trusted visibility into how data, applications, and AI systems interact so they can make better-informed decisions. I look forward to applying that principle inside Gigamon and working with customers as they evolve their security strategies for the Hybrid AI era.”
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