POLITICO spoke to more than a dozen European diplomats and State Department officials about the possibility of a second Trump term. And while none would go on the record, for fear of drawing White House ire, they were unanimous in their prediction that four more years of Trump would represent a notch up on the Richter scale, making the last few years of instability feel like a light tremor in comparison.

Emboldened by reelection, Trump would be unconstrained by virtually any norm or advice, the diplomats said. A second term would have a “definite disproportionate effect” on global politics, said one. Multilateral systems would likely shatter. A new geopolitical order would emerge. “Surviving another four years will require a very different strategy,” said one Northern European diplomat. “We need to be prepared for a sustained period of retreat” by the U.S.

At the global level, a second Trump term could mean the outright collapse of institutions like the World Trade Organization, and an economic decoupling from China. At the transatlantic level, today’s disputes over trade and defense would likely escalate, forever changing the relationship between the U.S. and Europe. Many European diplomats also fear that Trump could drag the U.K. further away from the European Union than even some Brexiteers would like.

The concern is not confined to foreign envoys.