The UN Security Council should convene immediately to “fight the Kremlin’s nuclear blackmail,” the Ukrainian government demanded on Sunday after Russian President Vladimir Putin disclosed plans to place tactical nuclear weapons in Belarus.

One Ukrainian official claimed that Belarus was “taken as a nuclear prisoner” by Russia.

Moscow, though, claimed that it was acting in response to the West’s escalating military support for Ukraine. In a televised interview that aired on Saturday, Putin made the announcement of the plan, claiming that the UK’s decision to supply Ukraine with depleted uranium-tipped armor-piercing shells earlier this week was the catalyst.

According to Putin, by stationing its tactical nuclear weapons in Belarus, Russia was imitating the US. He mentioned Washington’s nuclear arsenal. He declared, “We are doing what they have been doing for decades, stationing them in specific ally nations, constructing the launch pads, and training their crews.

In a statement released on Sunday, the foreign ministry of Ukraine denounced the action and called for an urgent meeting of the UN Security Council.

The UK, China, US, and France, who are permanent members of the UN Security Council and have a special responsibility to prevent threats of aggression using nuclear weapons, should take effective action to counter the Kremlin’s nuclear blackmail, according to the statement. “Against someone who threatens the continuation of human civilization, the entire world must unite.”