His former colleagues at the National Security Agency credit Mr. Inglis with leading the agency through one of the darkest periods in its history, after leaks from Edward J. Snowden, a former contractor who stole tens of thousands of classified documents and shared them with journalists.

His arrival in the Biden administration comes as the United States is contemplating responses to the Russian SolarWinds operation, in which hackers got into network management software used by most of America’s largest companies and many government agencies, and what appears to be a Chinese exploitation of Microsoft servers.

The administration’s response to those attacks is likely to come before Mr. Inglis is confirmed, which will likely take months. Jake Sullivan, the national security adviser, has promised a series of “seen and unseen” responses to the SolarWinds attack. Officials have said a public response is coming, but no announcements are expected this week.

Some in the Biden administration had worried about creating competing power centers by appointing a national cyber director. But officials said their concerns had been resolved by tapping Mr. Inglis, someone who has strong ties on Capitol Hill and has worked closely with Anne Neuberger, the deputy national security adviser at the White House for cyber issues.

Mr. Inglis, Ms. Neuberger and Ms. Easterly have all worked closely together in the past. While some critics of the National Security Agency have questioned the fact that all three spent significant portions of their careers at the agency, others described the experience as an asset.

“I can’t think of anyone who has more unique insight into the history, creation and congressional intent behind this position,” said Frank J. Cilluffo, the director for Auburn University’s McCrary Institute for Cyber and Critical Infrastructure Security, who served on the commission with Mr. Inglis. “He knows what it will take to fulfill the mission and to succeed.”

Colleagues describe Ms. Easterly, a graduate of the United States Military Academy at West Point who holds a master’s degree in philosophy, politics and economics from the University…