Ukraine’s official air-raid alert app was reportedly compromised, triggering false radiation warnings, according to the country’s Air Force.
For a brief period, the application warned users in Kyiv and several other locations that they were facing a nuclear threat.
The false notifications later stopped, with Ukrainian military officials confirming the disruption on Sunday night.
In a Telegram statement, the Air Force said the air-alert application appeared to have been targeted by hostile interference.
“There is no radiation threat. Remain calm and rely on updates from our official channel,” the message said.
Asked whether the incident involved a cyberattack, Ukrainian Air Force spokesman Yuriy Ignat replied: “Yes, it has been hacked.”
The suspected breach occurred just minutes after a ceasefire between Moscow and Kyiv ended in Ukraine’s eastern Kherson region.
The locally agreed pause in fighting began on Tuesday and was the longest truce recorded during the war.
The bogus notifications began on Sunday night and warned of radiation and chemical dangers. Pictured: A screenshot of the alerts sent in Ukrainian
The suspected hack was reported minutes after the truce between Moscow and Kyiv ended in Kherson. Pictured: Ukrainians embrace after being evacuated from the temporarily Russian-occupied city of Oleshky in the Kherson region
Ukraine’s Centre for Countering Disinformation cautioned that the threat information being displayed by the application did not reflect the actual situation.
The nationwide app is designed to provide real-time warnings about possible Russian air strikes across Ukraine.
In some cases, residents may have only a few minutes to reach safety, including when a ballistic missile attack is detected.
SPRAVDI, Ukraine’s Centre for Strategic Communications, accused Russia of being behind the suspected cyberattack in a post on X.
Kyiv authorities said a separate warning system dedicated specifically to the capital continued to operate without problems.
The BBC reported that the messages began at approximately 10.47pm local time. The first notification stated: “Radiation threat. A radiation alert has been declared in Kyiv.”
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One minute later, another alert claimed: “Hello. There will be a nuclear alert throughout Ukraine. Do not panic, Oreshnik is flying.”
A third warning, issued at 10.49pm, read: “Chemical threat. There is a danger of a chemical attack on Kyiv. Do not go outside.”
Seconds afterward, a fourth message falsely announced: “Street fighting threat. Street fighting is taking place in Kyiv. Do not go outside.”
Several all-clear notifications were sent soon after the series of false warnings.
It comes after the longest truce of the war, limited to the eastern Kherson region, ended on Sunday after Russia refused the offer of an extension, according to Ukrainian officials.
The rare pause in fighting, brokered by US First Lady Melania Trump and which began early Tuesday, enabled a humanitarian mission to the Russian-occupied city of Oleshky as the war grinds through its fifth year.
Neither side reported violations after the truce began, in what one Ukrainian lawmaker described as the ‘biggest de-escalation since 2022’.
‘The ceasefire, which was in effect from October 27 to November 1, has ended,’ said Ukraine’s Parliament Commissioner for Human Rights, Dmytro Lubinets.
He called the temporary truce ‘an important step in our joint humanitarian efforts’ with Russia.
An estimated 2,000 civilians were in Oleshky when the temporary truce took hold.
They were offered the choice of evacuating to territory controlled by Ukraine or Russia, or remaining in the city with replenished food and medical supplies.
For the safety of those who have stayed, exact numbers were not released after the evacuation.
At the Ukrainian border on Saturday, family members waited for a glimpse of their loved ones, while residents of nearby villages lined the highway waving flags and flashlights to greet the humanitarian convoy.
But Moscow and Kyiv have continued aerial strikes elsewhere, with Ukrainian President Volodymyr Zelensky saying on Sunday that Russia continues to target Ukraine’s energy systems ahead of winter.
US-mediated talks between Russia and Ukraine are set to resume this month, having been effectively frozen since the United States and Israel launched joint strikes on Iran in February.