The presidency of Donald Trump has the potential to be a revolutionary moment in global politics. The new US president appears to reject some of the basic principles on which American foreign policy has been based since the end of the Second World War. Ever since 1945, all US presidents have shared a commitment to an international order built around two central pillars. The first pillar is the promotion of international trade. The second is a global security system based on a network of US-led alliances.

But during his campaign for the presidency, Trump threatened to pull down both pillars. The 45th president of the United States is an avowed trade protectionist. And he is also a man who has consistently questioned the value of US-led alliances – calling NATO ‘obsolete’ and suggesting that America’s alliances with Japan and South Korea are bad deals for the US. The question is what will happen when Trump’s big ideas collide with the real world? Here is an issue-by-issue guide to the main places and problems to watch out for in 2017:

RUSSIA

Trump is an open admirer of Vladimir Putin. The new US president’s desire for a rapprochement with the Kremlin could lead him to lift sanctions on Russia and to accept the annexation of Crimea. But any such policies are likely to bring Trump into direct conflict, with the US intelligence community and with influential members of his own Republican party. The new president poured scorn on the CIA’s assessment that Russian hacking had played a part in the American presidential election. But can he afford to have a poisonous relationship with such a powerful interest group in Washington? After all, Trump will need the CIA’s assessments to guide him through some of the most dangerous issues he faces – including North Korea.

NORTH KOREA

The biggest looming security crisis facing Trump is probably North Korea. By the end of the Obama years, concerns were mounting in the White House that North Korea is getting dangerously close to being able to fit a nuclear warhead onto a ballistic missile that could hit the west coast of the United States. It is conventional wisdom in the US security establishment that a North Korea armed with ballistic nuclear missiles is an intolerable threat to the US. Trump’s initial comments on the subject suggest that he believes that increased pressure from China could force the North Koreans to abandon their nuclear programme. But gaining Beijing’s co-operation could be impossible – against a background of rows over trade and Taiwan. Faced with frustration over North Korea, Trump may be tempted to revisit some of the military options that were discarded by President Obama as too dangerous.

TRADE

During the election campaign, Trump was visceral in his denunciations of China, proclaiming that, ‘We have a $500 billion deficit with China … We can’t continue to allow China to rape our country … It’s the greatest theft in the history of the world’. Those who hoped that Trump would abandon protectionism, after winning office, were quickly disappointed. On the contrary, the new president placed protectionists in key positions in his administration. Peter Navarro, author of a book and film called Death by China, was appointed to head a new National Trade Council, based in the White House. Navarro’s intellectual ally, Wilbur Ross, is Commerce Secretary.

Navarro’s film begins by urging viewers – ‘Don’t buy made in China’. It points out the considerable loss in US manufacturing jobs, since China joined the World Trade Organisation in 2001, and blames this on a range of ‘unfair’ Chinese trading practices – including lax environmental standards, currency manipulation, intellectual property theft and illegal export subsidies. Some of the ills that Navarro highlights – such as commercial espionage – are real enough. Other complaints, such as the charge of currency manipulation, are outdated.

If Trump follows through on his threat to impose swinging tariffs on Chinese goods, he would certainly provoke retaliation. A trade war would ensue, poisoning commercial relations between the first and second largest economies in the world – and damaging the entire global economy.

CHINA

The threat of a real war between the US and China has also risen, following Trump’s election. The deliberate but careful attempts of the Obama administration to push back against Chinese ambitions in the Asia-Pacific region are likely to be replaced by a new Trump approach that is much more openly confrontational, and more impulsive in style. Even before taking office, the new US president demonstrated his willingness to antagonise Beijing – by taking a phonecall from the president of Taiwan, something that all US presidents have refused to do, since the normalisation of relations between the US and China in the 1970s. Mr Trump has also endorsed a significant expansion in the US Navy, which could signal a more aggressive American rejection of Beijing’s ambitions in the South China Sea. If there is a broader strategic thrust to Mr Trump’s thinking, it could be to split apart the informal alliance between Russia and China – and instead form a Washington-Moscow axis, designed at containing Chinese influence.

EUROPE

There are crucial elections in France, the Netherlands and Germany this year. There is now fear in the French and German governments, that Mr Trump may seek to help the European far-right – by supporting Marine Le Pen in the French presidential elections in May, the Party for Freedom in the Dutch elections in March and the Alternative für Deutschland party in the German elections in September. In that case, both the Kremlin and the White House would be working towards the defeat of the German chancellor. Such a scenario would once have been unthinkable. But it is possible in the new Trumpian world.

BREXIT

One huge disruptive factor for the global economy and for the Western alliance is Britain’s determination to leave the EU. The formal negotiation process is likely to begin in early 2017. It is unlikely to go well because the gap between the expectations of the British and EU sides is enormous. The British want to restore control over immigration from Europe and restore the supremacy of UK law – while maintaining complete free trade with Europe. The EU will refuse to do this.

Unfortunately for the UK, the negotiating process hugely favours the EU because if no new agreement is reached, the UK will simply fall out of the EU after two years – with potentially chaotic consequences for trade and migration. Faced with this nightmarish situation, the British may look to the Trump administration for assistance – either in the form of pressure on the EU, or through the offer of an alternative free-trade deal with the US. That, however, would be very hard to deliver quickly.

IRAN

Republicans in Congress share Trump’s disdain for President Obama’s nuclear deal with Iran. Some of the new president’s key appointees – including General Michael Flynn, his National Security Advisor – are particularly noted for their hostility towards Iran. But, in the long term, ripping up the nuclear deal could put the US on the road to a war with Iran. Will Mr Trump be prepared to take that risk?

TURKEY

Some investment bankers have talked of a fragile five countries, made up of South Africa, Brazil, Indonesia, India and Turkey. These five are said to be defined by their reliance on foreign capital. But, of the five, by far the most fragile looks to be Turkey – for reasons that are essentially to do with geopolitics.

The backwash of the Syrian war is now seriously destabilising Turkey. The country now hosts more than 3m refugees and has been hit repeatedly by terrorist attacks. It is also bitterly politically divided as President Erdogan seeks to consolidate his power – and purges both the press and the civil service. The year has started with the Turkish currency plunging. And given Turkey’s significance – on issues ranging from refugees to the NATO alliance – turmoil there will inevitably affect Europe and the wider West. It cannot simply be ignored.

THE MIDDLE EAST AND TERRORISM

Trump has consistently advocated a much more ferocious approach to the war on ‘radical Islamic terrorism’. But his advisers disagree about what that might mean. Some want the US military to go plunging back into the Middle East. Others argue that such a policy would push America back into the quagmire of war – while provoking new terror attacks. They will advocate a more isolationist approach that focuses on homeland security.

STYLE

Will Trump become a more conventional politician, as he settles into the Oval Office? The early signs suggest not. Foreign leaders may have to get used to the idea that changes in US foreign policy can emerge from a 3AM Tweet from the White House. Trump supporters relish the new president’s confrontational style and his willingness to question the conventional wisdom – which they see as a refreshing contrast to the professorial style of Obama. Trump’s critics fear that the new president will blunder into crises and will make the world a much more dangerous place. In 2017, we will learn which theory is closer to the truth