CrowdStrike and Delta are fighting over who is responsible for the airline’s cancellation of thousands of flights

CrowdStrike, a cybersecurity software company, is challenging Delta Air Lines for liability for damages suffered by the airline after a global technology outage.

Delta CEO Threatened to Sue CrowdStrike for What He Said Was $500 Million in loss of income and the additional costs associated with thousands of cancelled flights.

A CrowdStrike lawyer, however, believes the company’s liability should be less than $10 million.

Michael Carlinsky said in a letter to Delta attorney David Boies on Sunday that the airline’s lawsuit threat “contributed to a misleading narrative that CrowdStrike is responsible for Delta’s IT decisions and response to the outage.”

CrowdStrike’s attorney questioned why other airlines recovered much more quickly from the outage. He said the software company took responsibility for its actions “while Delta did not.”

A faulty CrowdStrike software update on more than 8 million computers running Microsoft Windows disrupted airlines, banks, retailers and other businesses on July 19.

Last week, Delta CEO Ed Bastian spoke on CNBC about the threat of legal action. He said Delta is more dependent on Microsoft Windows than other airlines. The Atlanta-based airline has hired Boies’ law firm to handle the case.

Bastian said CrowdStrike did not offer to help Delta beyond offering free advice. CrowdStrike said its CEO, George Kurtz, personally reached out to Bastian to offer help but received no response.

The U.S. Department of Transportation is investigating why Delta It took longer to recover than other airlines. Transportation Secretary Pete Buttigieg said his department would also review complaints about Delta customer serviceincluding long waits for help and reports of unaccompanied minors being stranded at airports.