KYIV, Ukraine (AFP) — Ukrainian President Volodymyr Zelensky and the US embassy in Kyiv issued warnings Saturday about the risk of a major Russian airstrike in the coming hours.

Their alerts came after Russian officials said the death toll from a Ukrainian strike on a college and its dormitory in a Russian-occupied town in eastern Ukraine had risen to 18.

Zelensky, posting on social media, said: “Our intelligence services reported receiving data, including from American and European partners, about Russia preparing a strike with the Oreshnik missile” — a Russian, nuclear-capable device.

Zelensky said they were checking the information, adding: “We are seeing signs of preparation for a combined strike on Ukrainian territory, including Kyiv, involving various types of weaponry.”

Appealing to the international community, Zelensky said: “Pressure must be put on Moscow so that it does not expand the war.”

The US embassy in Kyiv said it had “received information concerning a potentially significant air attack that may occur at any time over the next 24 hours”.

In the message, posted on its website, it said its alert was for all parts of Ukraine.

Last week, Russia’s army conducted three days of nuclear weapons drills involving thousands of troops across the country.

Russia has deployed the Oreshnik to Belarus, its neighbouring ally, which as well as bordering Ukraine, has borders with three NATO member states: Lithuania, Latvia and Poland.

Both Zelensky and the US embassy in their messages, called on their citizens to seek shelter in the event of an air alert.

Russia has so far used the Oreshnik against Ukraine twice, with conventional warheads: once in November 2024 against a military factory; and again in January 2026 against an aeronautics factory in the west of the country.

Russian President Vladimir Putin promised a military response after the deadly Ukrainian drone strike on Starobilsk in the Russian-occupied Lugansk region, launched overnight Thursday to Friday.

Kyiv has denied targeting civilians and said it had hit a Russian drone unit stationed in the Starobilsk area.