The former president’s protectionism-based quest to re-shore manufacturing jobs, his onslaught against climate policies, and his courting of Russian leader Vladimir Putin each gave serious headaches to a bloc that once considered the U.S. a major ally. 

Now, the head of the European Union’s top financial institution is bracing the continent and investors for Trump’s potential return to the Oval Office and the fresh economic woes it could bring.

“If we draw lessons from history, by which I mean to say the manner in which he carried out the first four years of his mandate, it is clearly a threat,” Christine Lagarde, head of the European Central Bank (ECB), said of a Trump return on news channel France 2 TV.

“You just have to look at the trade tariffs; you just have to look at his commitment regarding NATO; you just have to look at his attitude regarding the battle against climate change.

“In these three areas alone, in the past, U.S. interests were not aligned with those of Europe.”

Indeed, during Trump’s four-year tenure as the leader of the free world, it was difficult to find many areas where the EU and the U.S. were aligned on policy, and easy to find gaping holes in the major ones of defense, the economy, and climate.

NATO and Ukraine

Trump has repeatedly vented his dislike of NATO, the Western military alliance regarded as a shield against its members’ enemies, namely Russia. He often threatened to pull out of the organization owing to the U.S.’s outsize financial contributions to it.

Speaking to Politico, French European Commissioner Thierry Breton alleged that Trump told European Commission President Ursula von der Leyen that the U.S. would “never come to help you and support you” if it was under attack.

“By the way, NATO is dead, and we will leave; we will quit NATO,” Breton reported Trump as saying this week. 

From a military standpoint, the stakes for Europe are much higher than when Trump first assumed office in 2017. 

Russia’s invasion of Ukraine is stretching into its third year, and the U.S.’s current support for the embattled nation—having directed $75 billion in aid to Ukraine—is at odds with Trump’s more isolationist view of the world. 

Speaking to France 2 TV, however, the ECB’s Lagarde argued a Ukraine-friendly U.S. Congress would likely intervene in any attempt by Trump to pull resources from the country. 

Still, several diplomats told Reuters that a second Trump presidency may see the likely Republican 2024 candidate place loyalists in key positions in the Pentagon, State Department, and CIA to help him more effectively shape his anti-globalist vision than in his first term. 

Trade War II

Aligned with Trump’s aggressive rhetoric on defense have been harsher actions against old trade partners. 

The billionaire was elevated to the White House with a promise to fight back against globalization and return jobs to the U.S., particularly in Rust Belt states that saw old manufacturing powerhouses hobbled in the second half of the past century.

He sparked several trade wars to secure these aims, the largest of which was with China. 

Many products from China were hit with a 25% import tariff, leading to retaliation from the world’s second-biggest economy. 

Those tariffs have largely stayed in place since Biden took office in 2021, but most analysts expect the president to double down in what is increasingly becoming the Cold War of the 21st century.

However, Trump also targeted allies in his multilayered trade war during his first term. 

The former president placed tariffs on EU steel and aluminum imports in a bid to protect the domestic industry. 

The EU retaliated by placing tariffs on the import of goods including whiskey and motorcycles. However, the U.S. tariffs were paused under the Biden administration and remain so until after the 2024 election.

And if recent reports are anything to go by, those previous policies targeted at allies would be small-fry compared with what he has planned next.

The Washington Post reported that Trump has discussed a 10% tariff on all foreign imports to the country, including from the EU. 

Alan Wolff, a visiting fellow at the Peterson Institute for International Economics, argued in Fortune that retaliatory action would inevitably hurt the U.S.

It might also accelerate the trend of “friendshoring” as countries increasingly look to political allies to do business, while placing more pain on the fragile European economy. 

Climate back in the spotlight

Trump’s manic pursuit of U.S. growth also saw him kick ambitious global climate targets to the curb during his first term. 

In 2017, the climate change skeptic pulled the U.S. out of the historic Paris climate accords, a deal signed by predecessor Barack Obama aimed at keeping global temperatures from rising more than two degrees Celsius above preindustrial levels. 

The former president said the deal placed “draconian financial and economic burdens” on the country.

Biden signed the U.S. back up to the agreement on his first day in office in 2021.

While undermining Europe’s environmental targets, Trump’s pro-industrial strategies are also likely to hurt the competitiveness of the continent’s economy, many nations of which are facing down a potential recession.

Lagarde’s warnings against Trump are only likely to get louder as the U.S. gets ready to go to the polls in November, and the EU economy continues to battle slow growth.