United Airlines said it would resume services after grounding all domestic flights following a computer glitch on Sunday.
International flights were not affected, the Federal Aviation Administration said. The number of flights that were affected was not known.
"The ground stop has been lifted. We're working to get flights on their way," the company said in a tweet. http://bit.ly/2jQRW6B "We are working as quickly as possible to resolve this issue and get out customers to their final destinations," a company spokeswoman Maddie King said in an emailed statement earlier.
United was just one of several US airlines to experience disruptions due to glitches last year, an issue that prompted some to blame Texas-based Sabre Corp, a software company.
In October, thousands of United passengers were delayed worldwide after a computer glitch temporarily halted departures.