A top security adviser to Ukrainian President Volodymyr Zelenskiy said on Sunday that Russian plans to station tactical nuclear weapons in Belarus would destabilise that country, which he said had been taken “hostage” by Moscow.

Russian President Vladimir Putin announced the decision on Saturday, sending a warning to NATO over its military support for Ukraine and escalating a standoff with the West.

Although the move was not unexpected and Putin said it would not violate nuclear non-proliferation promises, it is one of Russia’s most pronounced nuclear signals since the beginning of its invasion of Ukraine 13 months ago.