The messages, which began around 10:45 p.m. kyiv time (3:45 p.m. ET), warned residents not to go outside due to the danger of radiation, the chemical threat and street fights. Another message professed, in Russian, that all of Ukraine was under nuclear alert. “Don’t worry,” he added. “Oreshnik is in action,” referring to Russia’s nuclear-capable hypersonic missile. That message referred to a Telegram channel called Hitcorecorp. Mash, the main pro-Kremlin Telegram channel, said it spoke to the group and took responsibility for the attack. NBC News was unable to verify who the group is and whether it was responsible for the alerts. Shortly after the alerts were issued on Sunday night, Ukraine’s air force said the country’s “Air Alert” app had likely been “compromised by the enemy,” confirming there was no “radiation threat” and urging calm. In separate statements, the app’s creators said that “unauthorized third parties interfered with the operation of the app,” forcing them to temporarily suspend operations. It later called the incident a “cyberattack” and said it was gradually restoring service. “The team is taking additional steps to secure the app to avoid similar situations in the future,” one of the statements read. Ukrainian media reported that users across the country received the alert, and authorities in the western Lviv region reported that some of the public warning sirens and public address systems issued a “radiation danger” signal. Still, many Ukrainians did not seem overly alarmed or terrified by the alerts. In fact, many shared memes online, mocking what they considered a blatant fake and the fact that the warning was issued in Russian. “No one was particularly surprised,” wrote one user on X. “They might as well have launched a dinosaur attack.” 00:44Russian drone strikes in Ukraine kill two teenagers 00:0000:00Ukraine’s state emergency service said Monday that the national alert system was functioning normally and an NBC News producer in kyiv experienced no further problems with the “Air Alert” app. Meanwhile, Russia’s Emergencies Ministry also said earlier Monday that its mobile app had suffered a “massive cyberattack,” resulting in what it said was “dissemination of false information to the public.” The public alert system was restored and was operating normally, he said shortly afterward. He emphasized that the application was only “an additional and complementary information service.” Screenshots shared by Russian media and some regional authorities suggested that the alert, issued in Russian, warned of “nuclear warheads” launched against Russia. As with the Ukrainian alert, the wording was informal and did not appear official. Russian authorities did not say who was to blame for the alleged cyberattack, only saying that “malicious actors” were behind it. It was not immediately clear if the two incidents were related. It happened just hours after a temporary ceasefire between kyiv and Moscow ended in the occupied Kherson region of southern Ukraine. The truce, negotiated with the participation of first lady Melania Trump and Pope Leo XIV, remained without violations by either side for six days, allowing the evacuation of hundreds of residents from the border town of Oleshky, which had been on the brink of a humanitarian catastrophe.
