The weaponisation of energy when Russia invaded Ukraine has given way to “weaponising everything” since Donald Trump returned to the White House, Germany’s former economy minister has said.

Robert Habeck, the Green politician responsible for keeping the lights on during the last energy crisis, said the belief gas “would never be a political weapon” led successive German governments blindly into Putin’s trap by building the Nord Stream pipelines and selling strategic reserves to Gazprom, which Russia emptied before the invasion.

But the re-election of Donald Trump led to a second security shock with “dramatic, drastic … and far-reaching” consequences which include using tariffs and technology as weapons, he told the Guardian.

“From weaponising energy – bad enough – to weaponising everything, this is the lesson I hope everyone has learned,” said Habeck, vice-chancellor of the last German coalition government.

Europe faces a looming energy crisis after the US and Israel attacked Iran in February, prompting retaliatory strikes that shut the strait of Hormuz, through which 20% of the world’s oil and liquefied natural gas (LNG) flows.

Price spikes have sparked renewed calls for clean local energy and complaints Europe should have ditched foreign fuels faster.

Habeck, who raced to build LNG terminals and secure alternative gas supplies when Russia invaded Ukraine, said he faced “sleepless nights” during the last energy crisis over the prospect of telling industries to close factories if he failed to get them gas in time.

“The gas prices now in Germany might be high,” he said. “But that time there was a real threat that we don’t have any gas at all.”

He rejected criticisms that the focus on shifting suppliers and building import terminals risked stranding assets as the country cut pollution.

He also defended his decision in 2022 to delay the shutdown of Germany’s final nuclear power plants by just a few months, instead of letting them refuel and run longer. The centre-right Christian Democrats, who were in opposition at the time, criticised the economy ministry for not having conducted an open-ended review of the question. A parliamentary inquiry last year did not reach a conclusion.

“I personally wouldn’t have had any problems using [the reactors] for some years longer, if that would have been the end,” said Habeck. He said parts of the opposition had seemed to be using it as a “Trojan horse” to reopen the phaseout law, and that changing the rules to allow refuelling could increase generation to a level where it would “destroy the increasing market for renewable energy”.

Germany made 60% of its electricity from renewables last year, with coal and gas making up the rest. Habeck said he had grown “kind of agnostic” about the risks of nuclear power in Germany but remembered the Chornobyl disaster in 1986 and the radiation that coated Europe.

“There was no dancing in the rain, there was no kissing in the rain, there was no sleeping at the beach, because there was nuclear fallout everywhere,” he said. “We basically stayed at home, and I really said at the age of 16, this is not the form of energy that should govern my life.”

The Ukraine war prompted EU officials to speed up its permitting process for wind turbines and solar panels, which now make more electricity than fossil fuels, but analysts say they have been slow to cut energy demand, reduce waste and electrify activities such as driving and heating homes.

Germany introduced a handful of short-term measures to save gas at the start of the war, such as turning thermostats in public buildings down to 18C – “the people in my ministry sat there with winter jackets at their desks” – and sought to curb future consumption by phasing out gas boilers.

The policy, known as “Habeck’s heating hammer” by an aggressive tabloid campaign, turned heat pumps into objects of derision. Its renewable energy requirements are now being watered down by the conservative-led coalition government.

Speaking from Copenhagen, where he works as an analyst at the Danish Institute for International Studies, Habeck said Nordic nations that have embraced heat pumps laugh at Germany for its resistance to clean heating.

But he said his narrow focus on avoiding gas shortages led him to underestimate the level to which Germans were fed up with inflation and interference in their personal lives. He said he also underestimated the resistance from the people running the gas companies.

“Some of them I know personally – they are decent guys and I guess when they talk with their children they always say ‘yes, we have to change to save the planet’ and ‘global warming is a threat’ – but in the end as the company owners they have an interest,” he said.

The Greens were voted out of the coalition government in February 2025 amid a slump in the salience of climate and fierce attacks from parties that blamed Habeck for Germany’s economic woes. In a possible sign of recovery, they won state elections on Sunday in Baden-Württemberg, the wealthy heartland of the German car industry.

“I would say Germany has made its peace with a different form of heat systems, and electric vehicles are now really increasing,” said Habeck. “So yes, too late – and not only a month or a year but 10 years too late, looking to other countries – but due to the hard-fought decisions [it’s] basically on the right track now.”