Ukraine said unauthorized parties used its nationwide emergency mobile app late Sunday to send false warnings of a nuclear threat, chemical danger and unrest, then temporarily suspended the service before bringing it back online¹.

The app is used to warn residents of Russian missile and drone strikes¹. The Times of India said the fake notices appeared in English, Russian and Ukrainian, with spelling and grammar errors in the English versions¹.

One Russian-language notification, as reported by the Times of India, said, "There will be a nuclear threat across Ukraine. Do not worry, the Oreshnik is incoming," a reference to a Russian ballistic missile¹. The same report said other messages claimed high radiation levels, a chemical danger and public disturbances in Kyiv¹.

Ukraine's air-raid alert channel said unauthorized parties had interfered with the app and told users not to click links in suspicious notifications¹. The country's Center for Countering Disinformation advised following other emergency channels while the breach was addressed¹.

Ukrainian air force spokesman Yurii Ihnat said in a television interview that the attack had not affected the country's security or defense operations¹. The Times of India said there was little sign of widespread panic, with some social media users treating the messages as a joke¹.

A Russian Telegram channel linked to security services said the hacking group Hitcore claimed responsibility for the Ukraine breach; that claim has not been independently verified¹. It was not immediately clear who carried out the incident or whether it was tied to a separate event in Russia¹.

Russia's Emergency Situations Ministry said a false alert went through its app at about 2:45 a.m. Moscow time on Monday across 33 of 89 regions¹. The ministry said it had identified the vulnerability used and that text messages, broadcasts and municipal sirens still worked¹. Kremlin spokesman Dmitry Peskov said Russian agencies face constant cyberattacks and must improve digital security¹.

The incidents came as a limited ceasefire in Ukraine's southern Kherson region expired Monday¹. Who compromised the apps, how they did so, and whether the Ukraine and Russia cases are connected remain unconfirmed¹.