Fake alerts warn of nuclear danger as Ukraine and Russia report emergency app hacks

The messages, which began around 10:45 p.m. Kyiv time (3:45 pm ET), warned residents not to go outside because of radiation hazard, chemical threat and street fights.

Another message professed, in Russian, that all of Ukraine was under nuclear alert. “Don’t worry,” it added. “Oreshnik is in action,” referring to Russia’s nuclear-capable hypersonic missile.

Shortly after the alerts went out late Sunday, 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 “unauthorized third parties interfered with the operation of the app,” forcing them to temporarily suspend its operations. It later called the incident a “cyberattack,” saying it was gradually restoring the service. “The team is carrying out additional measures to protect the app in order to prevent similar situations in the future,” one of the statements said.

Ukrainian media reported that users across the country received the alert, and in the Western Lviv region authorities reported that some of the public warning sirens and loudspeaker systems broadcast a “radiation hazard” signal.

Still, many Ukrainians did not appear unduly alarmed or panicked by the alerts. In fact, many shared memes online, poking fun at what they saw as a blatant fake, and the fact the warning was issued in Russian. “No one was particularly surprised,” one user wrote on X. “They might as well have thrown in a dinosaur attack, too.”

The State Emergency Service of Ukraine said Monday the national alert system was operating normally, and an NBC News producer in Kyiv did not experience any further issues with the “Air Alert” app.

Meanwhile, Russia’s emergencies ministry also said early Monday that its mobile application has suffered a “massive cyberattack,” resulting in what it said was “dissemination of fake information to the public.” The public alert system was restored and was operating normally, the ministry said shortly after. It emphasized that the app was only “an additional, supplementary information service.”

Screenshots shared by Russian media and some regional authorities suggested the alert, issued in Russian, warned of “nuclear warheads” launched at Russia. As with the Ukrainian alert, the wording was casual and did not appear official.

Russian authorities did not say who was to blame for the alleged cyberattack, only saying “malicious actors” were behind it.

It was not immediately clear whether the two incidents were linked.

It came just hours after a temporary ceasefire between Kyiv and Moscow came to an end in the occupied southern Ukrainian region of Kherson.

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The truce, brokered with involvement from first lady Melania Trump and Pope Leo XIV, held without violations from either side for six days, allowing the evacuation of hundreds of residents from the town of Oleshky, which had been on the brink of a humanitarian catastrophe.

The truce amounted to the biggest de-escalation between Kyiv and Moscow since the war started in early 2022.

“On behalf of America, I commend Russia and Ukraine for their leadership and cooperation surrounding the Oleshky ceasefire,” the first lady said in a post on X on Sunday. “I hope Oleshky serves as a foundation for lasting peace between both nations.”

Ukraine’s Ombudsman ​for Human Rights Dmytro Lubinets said he was exploring opportunities for “further humanitarian initiatives” with his Russian counterpart, Yana Lantratova, adding that it was “important to maintain this mechanism of cooperation.”

Ukraine’s Armed Forces accused Russia on Monday of using the truce to rotate its units and fortify positions in the area. Kremlin spokesman Dmitry Peskov said that Kyiv also could have used the ceasefire to regroup, calling it a “completely common practice in such situations.”