Ukraine and Russia say their emergency alert apps were targeted for cyber attacks.
In Ukraine, the residents received warnings about "chemical threats" and "street clashes".
The Ukrainian Air Force later clarified that there was no immediate threat of nuclear war and attributed the messages to Russian interference.
Hours later, Russia also announced that the country's warning request had been disrupted due to a "massive ground-based cyber attack."
The Ministry of Emergency Situations of Russia announced that experts are working to restore and restore the operation of this system.