“America's Agitator, Donald Trump.”

Those were the words emblazoned on the cover of a recent issue of the German news magazine Der Spiegel, published shortly before the US presidential election kicked into high gear with the Iowa caucuses on February 1. When Trump lost that day to Ted Cruz, many of his opponents seemed to breathe a collective sigh of relief.

And then Trump swept to victory in New Hampshire's primary on Tuesday. On its website, Der Spiegel proclaimed Trump's victory “the agitator's comeback.”

Europeans, like many Americans, continue to watch the presidential election with a mixture of horror and amusement. But for some transatlantic observers, the rise of a fringe candidate like Trump is no joke: They believe a President Trump would be a threat to the very core of the post-war European-American relationship.

‘Incredibly dangerous'

“He is, from a European perspective – frankly from an American perspective too – incredibly dangerous,” said Jeremy Shapiro, Research Director for the European Council on Foreign Relations in London. “We have somebody who is completely outside the mainstream of foreign policy thought.”

Shapiro told DW that Trump is obsessed with the US getting what he feels it deserves.

When it comes to the transatlantic relationship, that means forcing European allies like Germany to pay more for US protection. It also means pressuring NATO's European members to shoulder more of the burden when it comes to dealing with local conflicts, such as the ongoing war in Ukraine. This would be in direct contradiction to the actions of the current administration, which just recently announced it would quadruple military spending in Europe to counter Russian aggression in the east. Meanwhile, Trump has openly praised Russian President Vladimir Putin.

“He's almost angrier with America's allies than with its enemies,” Shapiro said.

Parallels with the European far right

Jan Techau, director of Carnegie Europe, a Brussels-based think tank, agreed that it was “an absolutely horrendous outlook to think of [Trump] occupying the Oval Office.” He said if such a thing were to occur, “it would be a very, very hard scramble for the Europeans to make their voices heard.”

Techau said the billionaire's current popularity is a reflection of a certain portion -albeit a very large portion - of the American electorate that feels it has been short-changed by the establishment similar to the Europeans who support right-wing populists like Marine le Pen in France and Geert Wilders in the Netherlands.

He said that same anger was also driving the success of left-wing candidate Bernie Sanders – a man Techau said would be harmful for transatlantic relations as well.

“Where Trump is simplistic, Sanders is naïve,” he told DW, referring to the Democratic presidential candidate's assertion in November that the US must expand its NATO coalition to include Russia.

An American AfD?

Shapiro, on the other hand, said it was important to distinguish Sanders from Trump, emphasizing that the leftist Vermont senator shared far more values with Europeans than the New York businessman did.

“It would be like we were electing the Social Democratic party in Germany,” he said of a possible Sanders presidency, while Trump would be more akin to the right-wing Alternative for Germany.

Meanwhile, both men emphasized the unlikelihood of a Trump presidency. Techau said the American political system was working as it should, and while Americans and Europeans alike might be shocked by what they were seeing, they should comfort themselves with the knowledge that eventually more rational voices will win out.

Shapiro didn't have quite so rosy a view of this year's presidential election, however.

“I think that the entire race is troubling to a lot of Americans, and it should be troubling to Europeans, because it demonstrates a sort of deep strain of nativism and xenophobia that runs through a lot of the American electorate.”

Just how deep that strain goes remains to be seen.