Mr Donald Trump is not one to mince words: He says he doesn't care if the European Union breaks up, since it is "basically a vehicle for Germany" and calls Nato, Europe's main defence arrangement, "obsolete".

With these statements, the next US president drew sharp battle lines. He, British Brexiters and other eurosceptics on one side and the rest of Europe on the other.

That emerging divide is an unexpected gift for a faction that appeared to be in retreat after Brexit: European federalists.

If Mr Trump acts on his opinions, Europe will be faced with the necessity of playing a much more independent geopolitical role.

The US will be at best a situational ally, and at worst a competitor. That makes the idea of increasing European unity far easier to sell even to those electorates within the EU that have been sceptical of deepening integration.

Few European nations are big enough to face an increasingly dangerous and unpredictable world on their own. Since its passage last June, Brexit has boosted pro-EU sentiment in most big European nations. The latest Eurobarometer survey conducted by the European Commission shows that, compared with the spring of last year, the number of EU citizens who view life in the bloc positively has increased by a percentage point to 35 per cent, while the share of negative views dropped to 25 per cent from 27 per cent. A slightly higher percentage of Europeans - 81 per cent compared to 79 per cent - now support the freedom of movement, an EU tenet that most irritated Brexiters.

A devaluing national currency and the prospect of being locked inside the borders of their home country are dubious enticements.

Brexit, however, hasn't eliminated the strong eurosceptic streaks that exist in countries as diverse as the Netherlands and Italy. While it's clearer now that no country will seek an exit in the immediate future, a loose union in which the nation states play the first fiddle has been almost universally assumed to be on the cards for Europe. German Chancellor Angela Merkel, the leader of the EU's strongest member state, is a supporter of an EU led by nations, not the central bureaucracy in Brussels.

Mr Trump, however, is taking relatively mild post-Brexit concerns to a new level. He keeps insisting that US allies are not paying enough for their security, forcing the US to shoulder too much of the burden.

Raising defence spending to Nato's requisite 2 per cent of gross domestic product is not an option for most European countries. Only Greece, Britain, Estonia and Poland hit that mark last year, though more small nations will achieve it this year. It's not clear, however, whether even 2 per cent is enough for Mr Trump. The US outspends all European Nato members put together almost three to one.

What if Mr Trump wants European allies to spend proportionally to their population or territory? What if, in case of a credible threat, he makes a spur-of-the-moment decision on whom to support militarily - and whom not to support? This creates a tangible risk that wasn't there before he won the US election.

In most EU countries, a strong majority of European Parliament members already supports EU military integration, though the Scandinavian nations and Austria are opposed to setting up a common military headquarters. Mr Trump's opportunism is likely to increase that support, especially in countries close to Russian borders. If politicians whip up a fear of being left defenceless, Europe may even be able to overcome the major problem with deeper military cooperation - a lack of funding.

Brexit is likely to open a gap of €5 billion (S$7.6 billion) to €17 billion in the EU budget (a "harder" Brexit corresponds to a smaller gap because it will increase Customs tariff revenue), but a security structure to back up the suddenly less reliable Nato will be seen as essential and worthy of raising additional funds.

Another area in which the EU may want to stick closer together, thanks to Mr Trump, is trade. In recent months, free trade has been relatively unpopular in Europe.

A deal with Canada, many months in preparation, was nearly blown up by the opposition of a regional Belgian legislature.

The Transatlantic Trade and Investment Partnership, a pet project of Dr Merkel and US President Barack Obama, is highly unpopular in Germany. But now that Mr Trump is offering a sped-up trade deal to Britain, Europeans may start worrying about losing competitiveness, and a more proactive trade policy may become a bigger priority than it is today.

Though Dr Merkel is still a free trade advocate, the EU as a whole may become more restrictive when it comes to trading with the US and Britain while opening up to others.

The size of its market - bigger than the US one - makes the EU a formidable economic competitor, but a more competitive stance will require moving faster to eliminate the many internal barriers to business that don't exist in the US.

In other areas, too, Europeans may need to huddle closer together during the Trump administration. Mr Trump has sounded openly hostile to Dr Merkel, with her "disastrous" refugee policy, and to Germany - a new reality for Germans who, since the end of World War II, have got used to a generally friendly and supportive US. Pro-Trump websites single out Dr Merkel for fake stories and conspiracy theories. That may be fine with anti-German, nationalist voters throughout Europe, but Germany is the mainstay of the European economy, and for most EU countries, a good relationship with Berlin is more important than one with Washington.

Besides, Mr Trump is highly unpopular throughout the EU. They will be receptive to the message Dr Merkel transmitted after the recent Trump interview: "We Europeans have our fate in our own hands."

Mr Trump provides European federalists with an opportunity to counter-attack. One of them, Mr Antonio Tajani, an ally of former Italian prime minister Silvio Berlusconi and European Commission president Jean-Claude Juncker - emerged on Tuesday as the winner of a heated race for the European Parliament presidency.

Other advocates of closer integration will now raise their heads too. Calls for more unity, and more European self-confidence, are already heard from the likes of French Foreign Minister Jean-March Ayrault and German Vice-Chancellor Sigmar Gabriel, both advocates of a closer-knit EU.

The Age of Trump will not last forever but he may do enough damage to the US relationship with Europe that Europeans may find it to their benefit to be prepared for similar shocks in the future.

BLOOMBERG VIEW