The Brexit vote
The first reason US-EU relations won't return to their previous state predates Trump even taking office — the Brexit vote.
For decades, the United Kingdom was America's first port of call when dealing with Europe.
While it sometimes stood against the prevailing winds in the EU, London served as a reliable and effective advocate in the bloc for the US.
The US must now invest even more time and energy in its relations with the politicians and institutions of the EU without appearing to give the UK short shrift; Anglo-American defence and intelligence ties are still valuable enough to warrant special attention from Washington.
After all, it is the UK that most closely shares the US view on geopolitical issues like Russia and China (more on that below). On the other hand, the Biden Administration shares the EU's (and Ireland's) assessment of the challenges reinstated by Brexit in Northern Ireland.
Brexit will make navigating the UK and EU relationship much more challenging for the White House, especially as the UK and EU remain at loggerheads for the foreseeable future.
Broader values
The second dividing line between the US and Europe is on the broader values which underpin policy choices.
On economic issues, the Trump era awakened in US politicians the realisation that they need to more proactively tend to matters at home.
For Democrats, that means more assistance for US workers and more industrial subsidies.
This may sound more familiar in Europe but it will not prevent Brussels from defending its single market against what it perceives as unfair competitive advantages.
Add to this the EU's particular approach to 21st century concerns like climate change and digital services and you have a fairly high likelihood of new tariffs, regulations or both applying to US-EU trade.
Together with different approaches taken to issues like data privacy, the social contract, and freedom of speech, the "common values" the US and Europe once shared are getting difficult to align.
Friends and foes
But the most critical division is over geopolitics and the perceptions of who is a friend and who a foe.
The transatlantic relationship was at its strongest during the Cold War, when the Soviets presented a common enemy for both the US and Europe to focus on.
Today, some Europeans want closer relations with Moscow, seeing it as a critical energy partner; others want to give it the cold shoulder over Vladimir Putin's aggressive actions abroad and human rights violations at home.
But the real dividing issue between the US and Europe is China.
The US sees China as its main rival, across both the economic and national security (including technology) landscapes.
Europe may consider China a national security threat, but hopes to cooperate economically in areas of mutual interest with Beijing, as shown in the Comprehensive Agreement on Investment they signed in December.
It's hard to work closely together when you can't even agree on who your friends and who your enemies are. And without an external threat to unite them, the transatlantic relationship drifts further apart.
European leaders are happy to see a more traditional president like Biden back in the White House.
But relief that Trump is gone does not provide a basis for a strong relationship.
The transatlantic alliance is in decline, and so too the Western-led world order with it.
The sooner both sides understand that, the sooner they can begin building the new architecture required for a stronger, lasting relationship.
- Ian Bremmer is the president of Eurasia Group and GZERO Media and author of Us vs. Them: The Failure of Globalism. He is on Twitter and Facebook.
