Germany on Sunday condemned a decision by Russian President Vladimir Putin to station tactical nuclear weapons in Belarus, bringing the arms closer to the European Union.
The announcement was "another attempt at nuclear intimidation by Russia", an official in the foreign office told AFP.
Germany would not allow itself to be "put off our course" by Moscow's move, the source said on condition of anonymity.
"The comparison made by President Putin to nuclear sharing in NATO is misleading and does not justify the step announced by Russia," the source said.
Belarus would also "contradict" its own international declarations to be a nuclear weapons-free zone, they said.
Putin justified the move on Saturday, saying: "There is nothing unusual here either. The United States has been doing this for decades.
"They have long placed their tactical nuclear weapons on the territory of their allies," Putin said in an interview on Russian television.
