Authorities in Ukraine and Russia have reported cyberattacks on their emergency alert mobile applications, with Ukrainian users receiving fabricated warnings about dangerously high radiation levels in the capital, Kyiv, late Sunday.
Ukraine's air raid alert channel said in a Telegram post late Sunday that "unauthorized parties" had disrupted the app's operations, forcing a temporary suspension of the service. It also advised users against clicking links contained in suspicious notifications.
Ukrainian authorities said the app, widely used by residents to seek shelter during daily Russian missile and drone attacks, was restored overnight. The fake notifications included warnings of elevated radiation levels, chemical threats and public disturbances in Kyiv. They contained spelling and grammatical errors and were written in English and a mixture of Russian and Ukrainian.
One of the fraudulent messages referred to the hacking group Hitcore. Russian Telegram channel Mash, which has links to security services, reported that the group had claimed responsibility for the attack. However, the claim could not be independently confirmed.
Ukraine's state-run Center for Countering Disinformation confirmed the breach and urged people to follow emergency updates through social media channels and rely on physical warning systems while the issue was being resolved.
Yurii Ihnat, spokesman for Ukraine's air force command, said the incident had not affected the country's security or defence operations, as the application operates independently of military command systems.
Speaking to private television channel 1+1, Ihnat said the air force continued to communicate real-time threat information through separate channels, including widely used social media platforms.
In Russia, officials said Monday that hackers had gained access to the Emergency Ministry's mobile application and distributed fake emergency notifications.
The ministry did not identify those responsible but assured the public that the country's broader emergency alert system remained operational. It said the mobile application was only an additional service, while warnings were also delivered through SMS messages, media broadcasts, municipal sirens and loudspeakers.
Kremlin spokesperson Dmitry Peskov said Russian government agencies faced a constant threat of cyberattacks, including an increasing number involving artificial intelligence.
"All government bodies must take steps to improve the cybersecurity of our digital resources," Peskov said.
Limited ceasefire expires in Kherson region
Meanwhile, Ukrainian authorities in the war-divided Kherson region reported several Russian drone attacks early Monday, hours after a temporary humanitarian ceasefire expired.
The regional administration said a 62-year-old woman and a 73-year-old man were taken to hospital with blast injuries in Kherson city, located across the Dnipro River from Russian-occupied territory.
The localised truce ended at midnight as Monday began. The temporary suspension of fighting had been arranged to facilitate a humanitarian aid operation in the Russian-occupied city of Oleshky.
The ceasefire, which took effect on Oct 27, was the most significant pause in hostilities between Kyiv and Moscow since Russia launched its full-scale invasion of Ukraine nearly five years ago.
The White House said US First Lady Melania Trump had helped negotiate the limited truce. Civilian representatives from both Russia and Ukraine also contributed to the agreement, which enabled residents trapped in Oleshky to leave in an unusual joint evacuation operation that concluded Saturday.
Around 2,000 civilians were estimated to be in Oleshky when the temporary ceasefire began. They were given the option of evacuating to Ukrainian- or Russian-controlled territory or remaining in the city with additional food and medical supplies. Authorities withheld the exact number of evacuees to protect those who remained.
Ukraine's General Staff said Monday that Russian forces had strengthened their drone defence capabilities and replenished ammunition supplies in the region during the ceasefire.
Elsewhere, emergency services reported that Russian drone attacks injured 12 people in the eastern Kharkiv region and damaged a refrigeration facility, greenhouses and residential buildings.
Another five people were reported injured in the Black Sea port city of Odesa, where a warehouse was struck and several homes were damaged.
Russia's Defence Ministry said Monday that its air defences had intercepted 212 Ukrainian drones overnight.
Vyacheslav Fedorishchev, governor of Russia's Samara region, said local air defence units were responding to an aerial attack but provided no further information.
Independent Russian media outlets later reported that Ukrainian drones had targeted one of Europe's largest oil transportation hubs in the Samara region.