Ex-NSA chief Keith Alexander joins Amazon board

Amazon.com Inc said on Wednesday former National Security Agency chief Keith Alexander has joined the e-commerce giant's board.

Alexander, who is the co-chief executive officer of IronNet Cybersecurity Inc, will serve on Amazon's audit committee, it said in a regulatory filing.

The four-member audit committee, headed by ex-Reader's Digest chief Thomas Ryder, includes former PepsiCo CEO Indra Nooyi.

Alexander has served as the commander of the U.S. Cyber Command in addition to heading the Central Security Service.