Also at the press conference, President Putin has downplayed suggestions of a new nuclear arms race between Russia and the US. Earlier, US president-elect Donald Trump wrote on Twitter that the United States should greatly 'expand its nuclear capability'.

His comment alarmed non-proliferation experts, but Putin shrugged them off as "nothing new", and that Russia will not be drawn into a new arms race. 

"As for the newly-elect US President, Mr. Trump, there is nothing new here. During his election campaign he has spoken about the need to strengthen US nuclear capabilities, armed forces, there is nothing unusual about it," Putin said.