"Economic giant, political dwarf" -- that is how the world long viewed post-World War II Germany, the European export power reluctant to use military muscle in global conflicts.

It is an image that Europe's most populous country wants to shed as it gradually assumes a bigger defence role, within the frameworks of NATO and the European Union.

That ambition, the outcome of a debate that began two decades ago, is the message of Germany's new military roadmap, the defence ministry's so-called White Paper, to be released Wednesday.

It marks a shift for Germany which, burdened by guilt about Nazi terror and the Holocaust, for decades stepped softly on the world stage and long refrained from sending troops abroad.

The paper, the first of its kind issued in a decade, envisions a future defence union of European states -- reviving a 1950s-era idea that was rejected by France at the time -- as Europe is nervously eyeing Russia and digesting the shock of the Brexit vote.

"Germany is increasingly seen as a key player in Europe," says a draft of the document seen by AFP.

"Germany, a globally highly connected country... has a responsibility to actively help shape the world order," it says, vowing that the country is ready to "assume responsibility" and "help meet current and future security and humanitarian challenges".

- Paradigm shift -

The paper presents a paradigm shift for a country often lampooned as a "Bigger Switzerland" -- prosperous and seeking to stay neutral -- in the words of French economist Alain Minc.

While Germany's dark past has nurtured a strong pacifist tradition, its leaders have also often been stung by allies' criticism that they are not pulling their weight in tackling crisis hotspots, lack the stomach for full-fledged military engagement and prefer chequebook diplomacy.

It was not until 1994 that Germany's highest court allowed the country to participate in multinational peacekeeping missions.

Germany has since deployed troops to conflict zones, from the Balkans to Afghanistan and Mali, but has also earned criticism for staying out of other conflicts, especially the 2011 NATO intervention in Libya.

Over the past two years, President Joachim Gauck and Defence Minister Ursula von der Leyen have repeatedly argued that Germany must engage more forcefully abroad.

Berlin has since joined the international alliance against the Islamic State group, though in a non-combat role, sending Tornado reconnaissance jets, aerial refuelling planes and other support.

Germany, a major arms exporter, has also broken with another taboo -- sending weapons into an active conflict -- by arming Kurdish Peshmerga fighters battling IS in Iraq.

And at the NATO summit in Warsaw, Germany was one of the members to pledge to station rotating battalions in Poland, Estonia, Latvia and Lithuania from 2017 as a collective deterrent against Russian adventurism.

- 'European defence union' -

The new engagements come as the German army has complained of being overstretched, underfunded and plagued by equipment failures, including its G36 assault rifle, which reportedly doesn't shoot straight at high temperatures.

The Bundeswehr is now set to see its budget boosted and to get its first increase in troop strength since the Cold War, when it was still a conscript force, with plans to recruit nearly 20,000 personnel over seven years.

Germany, in order to reassure international partners, stresses in the White Paper that it will act within the trans-Atlantic and European frameworks.

"As a long-term goal, Germany aims for a common European security and defence union," says the text.

For now, this means using all ways of military cooperation authorised under the EU treaties and "strengthening the European defence industry" through tie-ups, with France in particular.

A former German chancellor, Gerhard Schroeder, presented an even more ambitious vision in an article co-authored with Minc, the French economist, in news weekly Die Zeit.

They proposes that Paris and Berlin "pool their resources" in foreign and security policy, and that their armed forces work together as closely as possible.

France, as a permanent member of the UN Security Council, would commit to presenting a common position with Germany, the authors suggested.

It is far from certain, however, that such an idea could gain traction now in France, a nuclear-armed military power whose politicians have been traditionally wary of German pacifism and still resent its abstention in the UN vote on the Libya intervention.