But media reports claim that it could be linked to the launch of an experimental missile by North Korea, an event that happened around the same time.
On January 11 at 2:30 p.m. local, The Federal Aviation Administration (FAA) ordered that all planes that were about to depart from the West Coast airports must be grounded. Less than fifteen minutes later, the order was revoked.
The North Korean missile launch was immediately detected by the North American Air Defense Command inside Cheyenne Mountain in Colorado. The unit determined it was not a threat to the U.S.
The temporary suspension of the flight operation in the United States normally only takes place in extreme weather conditions, but the weather was fine.
An FAA official later told Reuters news agency that the measure was related to "initial reports of events in the region". The FAA declined to go into detail about that, but the only logical explanation seems to be North Korea's hypersonic missile test that was taking place at the time.
The hypersonic missiles have no predictable trajectory and are, therefore, more difficult to trace and intercept. The speed of the Hypersonic Missiles is around Mach 5 (6,200 kilometers per hour). North Korea also has nuclear weapons and may be able to equip its missiles with nuclear warheads.