Russia's invasion of Ukraine has rattled NATO and led Berlin to pour huge amounts into rebuilding its armed forces, sparking a business bonanza for weapons makers and manufacturers of dual-use goods.

The Hanover Industrial Fair, focused on mechanical and electrical engineering and digital industries, still bars outright weapons technology, but this year it featured a Bundeswehr armed forces stand with a camouflage-painted helicopter and an electronic warfare simulator.

A new "Defence Production Area" grouped around 30 companies offering products with potential military applications -- among them the family-owned Roth company, which makes industrial components, including hydraulics.

"We see this as an opportunity, which is why we're exhibiting in this defence sector as well," said Monika Schwab, its the head of sales. "Because we say that we have the potential, with our expertise, to make our contribution in various fields, including in this area of defence."

The Hanover fair dates back to 1947 and has not traditionally featured the defence industry, a legacy of the dark shadow cast by Germany's Nazi and militarist past.

But it now is widening its horizons as Germany, with much of the rest of Europe, looks to strengthen its defences.

Among the guests this year was German Defence Minister Boris Pistorius, who noted that the event had "for the first time placed an emphasis on armament on this scale".

A country's "ability to defend itself begins with its businesses," he said.

- 'Very close partnerships' -

In Berlin, Pistorius stressed on Wednesday that Germany aimed to build the "strongest conventional army in Europe", with more troops and new tanks, aircraft, ships and AI-controlled drone systems.

As President Donald Trump casts doubt on the US commitment to NATO, Chancellor Friedrich Merz has turned on the funding taps, while German defence giants such as Rheinmetall are announcing major new projects each week.

The Hanover fair rolled out the red carpet for Rheinmetall CEO, Armin Papperger, who spoke about deterrence and the future of warfare, undeterred by interruptions from pacifist activists.

Papperger was flanked by Lieutenant General Christian Freuding and Marc Wietfeld, head of Arx Robotics, a start-up that supplies AI-equipped autonomous military vehicles to the German army and to Ukraine.

Arx Robotics did not have its own stand, but Wietfeld told AFP that it was "very important for me to be here".

He said the arms industry was once treated in Germany as akin to makers of "alcohol, tobacco, gambling and pornography" but had now "become a part of the economic and democratic fabric of society".

Wietfeld, a former soldier, predicted that pure defence companies would be allowed at the fair by next year.

"We need the ability to scale, and components from European supply chains," he said, adding that Germany's crisis-hit medium-sized companies "once again need reliable orders".

"That's how we grow together in very close partnerships."

-'Reticence starting to disappear' -

Most companies AFP interviewed in Hanover remained tight-lipped about the possible military applications of their products, a legacy of Germany's post-WWII aversion to militarism.

But Wietfeld says German "reticence" towards the defence industry "is starting to disappear".

In 2027, Germany will host the DSEI arms fair, usually held in London -- another development that has irked German pacifists, who are calling for its cancellation.

As the Ukraine war has raged, Germany, now the top supporter of Kyiv, has accused Russia of a campaign of sabotage, espionage, drone overflights and cyber attacks.

Growing fears about critical infrastructure and hacking also saw new businesses come to the fore in Hanover.

One German cybersecurity company there, SySS, invited visitors to use a model of a hydroelectric dam to simulate hacking it and flooding a village downstream.

"This is meant to illustrate that IT security vulnerabilities can in fact have drastic consequences in the real world," said the firm's Jannik Vieten.

"The aim is to raise awareness among energy suppliers and the manufacturing industry," he said, adding that "there really is a lot of catching up to do in IT security".

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