A senior advisor to Ukrainian President Volodymyr Zelenskyy says nuclear threats from Vladimir Putin need to be taken seriously, but told DW's Tim Sebastian that this is not the first time the Kremlin has sought to blackmail the world.

Ihor Zhovkva, who works in the president's office in Kyiv, said the world's nuclear powers needed to convince Putin to step back from nuclear threats as Russian forces continue to suffer setbacks in Ukraine — but that for now the only talks that will take place with the Kremlin are on the battlefield.