“During the Cold War, when Konrad Adenauer or Willy Brandt ruled, defence spending was between 3% and 4% of economic output,” Stoltenberg said, in a translation of an interview published in Germany’s Funke Mediengruppe newspapers at the weekend.

In his native Norway, he said, it was similar. “We managed it then, and we have to manage it again today.”

Stoltenberg recalled the decision of the July Nato summit in Vilnius, according to which 2% of gross domestic product for military spending was “the minimum” – though Berlin continues to fall short of reaching this target.

He said he expected many allies to exceed that target.

Stoltenberg said as a former prime minister of Norway, he knows how difficult it is to budget more money for defence when higher spending on health, education or infrastructure is also necessary. But if tensions rise, defence spending must be increased, he said.

Germany has “still not reached” the Nato target of investing 2% of economic output on defence, Stoltenberg stressed, but said the country was “well on its way.”

Stoltenberg was quoted as saying that it makes “a huge difference” as to whether a country like Germany “sticks to this target or not.”