An Italian band refused an invitation to perform at Donald Trump's inauguration as the 45th US president on Friday in Washington and some European representatives did not turn up. Meanwhile European TV viewers were left constantly shaking their heads as Trump delivered his inauguration speech.

These are signs of the mounting anxiety, distrust and even fear that ordinary Europeans have been feeling since the businessman won the US presidential election.

Without a doubt, Trump is expected to bring more uncertainties to Europe, mainly because his policies toward the European Union are still not clear, and his guiding principles are isolationism and nationalism, which he believes will make the United States great again.

During Barack Obama's presidency, relations between the EU and the US went through a dramatic change because of Washington strategically increasing its interventions in the Asia-Pacific region with its strategy of rebalancing to the Asia-Pacific.

In previous decades, the alliance partnership between the EU and the US has played a big role in shaping global governance by encouraging global exchanges, and they have shared their capital, knowhow and management expertise with less-developed economies.

However, most of the conflicts over that period have escalated mainly because of their interventions.

The transatlantic alliance will likely experience its biggest shift for decades during Trump's presidency, if his guiding principles do not change.

And the extent of the shift is likely to be evident soon.

First of all will be how Washington prioritizes its relationship between London and Brussels. Trump's taking power in the White House will be soon followed by the United Kingdom's commencing negotiations to leave the EU, so their respective bilateral relationships with the US will need to be rearranged.

London wants to maintain its "special relationship" with Washington, and British Prime Minister Theresa May will be the first foreign leader to be a guest at the White House. Their meeting will be on Friday, one week after Trump's inauguration.

Brussels has also indicated its urgent desire to meet Trump. EU leaders wrote a congratulatory letter to Trump in early November and invited him to hold a Washington-Brussels summit as early as possible.

This year's G7 summit will be in Italy in May and the G20 summit will be held in Germany in July. If he does not do so earlier, Trump may fly to Brussels to meet his EU counterparts then.

Second, the Transatlantic Trade and Investment Partnership, on which 15 rounds of talks have been completed, is at risk. Brussels is eager to reap such a deal and the current European Commission listed it as among its 10 priorities in late 2014.

Obama had the ambition to conclude the deal, but failed, and politicians in France and Germany, two vital countries within the EU, have publicly showed their disagreements with the TTIP.

The TTIP may easily suffer the same fate as the Trans-Pacific Partnership agreement.

Third, the security system in the EU's eastern and southern regions is also facing a testing time. Right now, NATO, with its huge presence and contribution from the US, has played a crucial role in ensuring the safety of the EU and its neighboring areas.

Europeans fear Trump has no interest in having the US work as the world's policeman and it may finally withdraw its military influence from Europe. How the European countries respond to that if it materializes will deserve close observation.

All in all, Trump will be bringing changes to this region and, hopefully, they will be positive and constructive in re-recognizing transatlantic relations. However, it is clear they are in for a testing time in coming months.

The author is deputy chief of China Daily European Bureau. fujing@chinadaily.com.cn