The US Federal Aviation Administration (FAA) lifted a nationwide ground stop on departing flights on Friday night. However, officials were still working to resolve the underlying issues, and flight cancellations and delays are expected to continue through the weekend.

More than 4,700 flights were canceled, leaving tens of thousands of travelers stranded.

At a White House briefing, Transportation Secretary Sean Duffy linked the disruption to overloaded switches and routers and called for $50 billion in upgrades to the US air traffic control system.

President Donald Trump and Homeland Security Secretary Markwayne Mullin said there was no indication of a cyberattack.

Friday's action marked the second nationwide ground stop on departing flights since the 9/11 attacks.