It happened at around 3pm on Saturday, in one of the conference rooms at Munich's Bayerischer Hof hotel, where politicians from around the world had gathered for an annual security conference. The female defence ministers of Norway, Sweden and the Netherlands had all met at previous conferences, so they decided to welcome Ursula von der Leyen, their new German counterpart.

When Belgium's (male) defence minister, Pieter De Crem, spotted the group of women, he quipped: "Oh, I'll better get out of the picture." That's when the Dutch defence minister, Jeanine Hennis-Plasschaert, asked someone to capture the scene on her phone.

Hennis-Plasschaert told the Guardian: "[The Dutch politician] Neelie Kroes once said to me that old boys' networks are the oldest form of cartels we have in Europe. She was right, but things are changing, and women can do similar things now."

Her tweet with the photograph soon went viral. To many, the image heralded a new era in which even the last bastions of male privilege were no longer closed to talented women. Sweden's foreign minister, Carl Bildt, retweeted it with the comment "True Power Girls" (and was widely criticised for the condescending tone).

"That's how global peace can be reached," read another comment. Others felt the photograph was less indicative of a smashed glass ceiling than the diminished importance of the defence ministry in the post-cold-war era.

While all four women hail from liberal-conservative parties in northern Europe, their paths to their current roles differ considerably. Whereas Sweden and Norway's defence ministers are already the third and fifth female politicians in their posts, their German and Dutch colleagues are breaking new ground.

Hennis-Plasschaert , 40, from the Netherlands' People's Party for Freedom and Democracy, entered the cabinet after a short but distinguished career in the European parliament in November 2012.

On taking office, she famously said that "it doesn't matter if you have a willy or not" and denies women have a common way of doing politics, or even a common experience of becoming politicians, purely because they are all women.

"I don't think the military officers that we work with see us any differently than if we were men," she said. "And if they do, they don't show it. But there is a public debate about women taking more influential political roles, and that's healthy."

Sweden's Karin Enström, 47, is the only one of the four women with professional experience in the armed forces. From an upper-class family and in office since April 2012, she still holds the rank of captain in the Swedish marines; her brother Henrik was once in charge of the small Swedish contingent in Afghanistan.

Ine Eriksen Søreide, 37, has been one of the rising stars of Norwegian politics since she was asked to chair parliament's education committee at the age of 29. Having impressed observers and colleagues with her people skills, determination and work ethic, many believe the young politician from a humble background is destined for higher things.

In the case of Germany's Ursula von der Leyen, there is little doubt that a successful stint in the defence ministry would set her up as the obvious successor to her party colleague and current chancellor, Angela Merkel.

The 55-year-old doctor, who has seven children, made her name as a strong supporter of parental leave during her stint in the family and labour ministry.

After elections in September, it was reported she insisted on taking the defence job; the male incumbent was swiftly moved to the interior ministry to make room.

Do female defence ministers prove to be more doveish in their roles than their male counterparts?

Not going by Von der Leyen's comments since taking office. She has already distanced herself from her predecessor's refusal to join military action in Libya, and recently told Der Spiegel that "due to globalisation, distant conflicts are now much closer to Europe".

At the Munich security conference, she underlined the German president Joachim Gauck's call for a more proactive German foreign policy by stating that "indifference is not an option for Germany".

Her Dutch colleague too called for a more robust European front on foreign interventions: "Reliability means that partners don't pull out of joint military commitments at five to 12," said Hennis-Plasschaert on Saturday.