Ingmar Neveus answers four questions about the flight stop in the USA

What has happened?

The stoppage of flights from all airports in the USA began around 21:45 Swedish time and was lifted just under five hours later.

Some international flights, from the US East Coast to Europe, have been able to take off even during the shutdown. Flights that were already in the air on their way to the US have also been allowed to land during the stop. But the FAA, the US Federal Aviation Administration, asked its European counterpart overnight to halt all future flights. How the situation is for European airlines on Saturday morning is unclear.

Shortly after 03:00 Swedish time, the first domestic flights in the USA have taken off, heavily delayed. More than 1.5 million travelers were stuck at hundreds of airports at the worst of the situation.

What caused the flight stop?

Many worry that a cyber attack is behind it. Was it perhaps Iran or Russia trying to harm the United States?

Homeland Security Secretary Markwayne Mullin said Friday night that the cause of the shutdown is a failure of the hardware that controls communications between 22 air traffic control centers in the United States.

He claims that there is no indication of a cyber attack or that hostile actors caused the flight chaos - "this is not a new 9/11". But he doesn't rule it out either.

- We are still looking at it. I'm not ruling anything out, he told media in the White House.

Attacks against freezers in Sweden and other European countries make many suspect foreign actors of sabotage right now. Mullin says thousands of Americans have contacted his staff about cyberattacks. Media in the US are also flooded with questions about this.

At the same time, experts point out that the FAA as recently as the other day installed a new AI-driven system on its computers. This system has nothing to do with air traffic control, but several experts still believe it may have indirectly caused the stop by overloading the FAA's computers.

Communication between air traffic control centers has not been updated for a long time. It is based to some extent on old technology, with copper wires, soft data disks and paper strips.

- Installing new software there is like putting a rocket engine behind a horse carriage, says CNN's aviation expert Miles O'Brien.

What happens now?

Thousands of aircraft and crews are now at the "wrong" airport, which means it will take time, probably several days, before everything is back to normal.

The stop shows how vulnerable aviation is in the United States. About two million people fly domestically here every day, and on Thursday the figure was almost 2.5 million.

In just under two weeks, the holiday of Thanksgiving falls in the United States. Then usually around three million fly domestically. Transport Minister Sean Duffy said on Friday night that everything should work by then. But he couldn't guarantee anything.

Expect major delays also for flights to the USA from Sweden and other European countries. All passengers are advised to contact their airlines for updated information.

Will there be any political consequences?

Ministers Mullin and Duffy praised Donald Trump several times during their press conference as "the best president ever".

At the same time, many here question the fact that Trump himself has not appeared and addressed the population directly. In the midst of the grounding, he devoted himself to posting on Truth Social about "bringing the entertainment industry back to the United States."

Transportation Secretary Sean Duffy repeated several times that he, and Trump, over the past year have asked Congress for tens of billions of dollars to update the FAA's air traffic control system. But not received it.

Several media outlets point out that Trump and the Republicans have had a majority in Congress for the past two years and should have been able to start this work already. They also point out that the Trump administration has focused on privatizing air traffic control in the United States.