Picture the scene. A US Air Force F-16 Falcon has come down over Syria. The pilot is being held by Islamic State which threatens to behead him. Video shows the pilot being tortured in a cage, while the terrorists taunt new US president, Donald Trump. The pilot’s family plead for the White House to save him. The drama is dominating the 24-hour TV news networks. It’s a media storm. What will Trump do?

Answer: nobody has a clue. Trump lacks military experience. He has never served in the armed forces. Nor does he have any background in diplomacy. What Trump does have, by all accounts, is a short fuse – a tendency to shoot first and ask questions later. His predecessors would have played for time, appealed to local allies, or pursued deniable, back-door talks while examining options for a rescue.

But president Trump is different. Unused to the awesome responsibility of the Oval Office, under fierce pressure to act, enraged by Isis’s personal jibes, infuriated by accusations of dithering, and determined not to show weakness, it is easy to imagine Trump making a wrong, hasty and disastrous call. With a few hot-headed words, translated into situation-room orders, Trump could not only lose the pilot, he could plunge the US inextricably into the quagmire of another Middle East war.

There are grave doubts about Trump's inexperience, volatile temperament and macho instincts

Grave doubts about Trump’s inexperience, volatile temperament and macho instincts also apply in other global hotspots where a US president’s actions, or inaction, are always critical and sometimes lethal. Here are five dangerous flashpoint issues that could suddenly and unpredictably test the novice president’s judgment, cool and common sense in the first 100 days of his tenure.

SYRIA AND IRAQ

The Isis hostage scenario is not wholly imaginary. In January last year, a Royal Jordanian air force pilot, Muath al-Kasasbeh, was captured and burned to death in a cage by the jihadis after negotiations for his release failed. Similar repeat incidents involving US, European and Arab members of the anti-Isis coalition, and local forces, are becoming more likely as the endgame in the fight against the Isis caliphate approaches.

The battle is being fought out on two main fronts. One is the siege of Mosul, northern Iraq’s principal city. Trump has criticised the conduct of the campaign, which involves the mainly Shia Iraqi army, Kurdish and Sunni Arab militias backed by 300 US special forces commandos. But he has not offered an alternative strategy.

Much the same holds true of the attempt to seize the Isis headquarters in Raqqa, in northern Syria. Trump says that defeating terrorism is a top priority and he will “bomb the shit out of Isis”. But nobody, including him, appears to know what this means in practice. If the battle goes badly, will he escalate? Will he carpet-bomb cities where millions of civilians live? Is he prepared to deploy US ground forces? What will he do if, as seems possible, both sieges become bogged down, or Isis begins mass, daily executions of civilians?

Trump is also silent about Turkey’s significant military intervention in Syria and Iraq and its parallel fight with the Kurds. President Recep Tayyip Erdoğan wants two things from Trump: an end to US support for the Kurdish peshmerga and the extradition of Fethullah Gülen, a cleric exiled in the US who he blames for last summer’s failed coup. With Isis on the back foot and the Iraqi and Syrian governments weakened, the Turkey-Kurd feud could explode at any time as the protagonists try to redraw national boundaries and compete for territory and resources.

RUSSIA AND EASTERN EUROPE

Trump has raised expectations that he can repair the US rupture with Russia. But a reset will come with a price. In the first instance, Vladimir Putin, Russia’s authoritarian president, will want a relaxation or scrapping of punitive sanctions imposed after Russia annexed Crimea in 2014. To dismay in Europe, Trump has suggested he may agree.

Putin also seems likely to get his way in Syria, where Russian forces have pushed his client, Bashar al-Assad, to the brink of victory in Aleppo and elsewhere. Trump has made no serious objection to Russian actions in Syria, even though the UN says they may constitute war crimes. He seems content to have Assad remain in power, or even to treat him as an anti-Isis ally.

However, the regime’s renewed use of chemical weapons, for example, new Russian atrocities, or a suddenly escalating humanitarian and refugee catastrophe could all trigger a new crisis that blows up in Trump’s face, forcing him to move against Putin. The idea of no-fly zones and civilian safe havens still has backers. If Trump goes down this route, he could end up directly confronting Russia’s military.

The European allies cannot do much about Trump’s Syria insouciance. But they will strongly oppose him if he tries to run down the Nato alliance, as he has suggested. Russian pressure on Nato’s easternmost members in the Baltic republics, Poland and Bulgaria – in terms of political meddling, disinformation, cyber attacks, missile deployments and military exercises – is reaching new heights. Influence-peddling and destabilisation operations are increasingly reported in Moldova, Montenegro and elsewhere in the Balkans. Eastern Ukraine remains a ticking timebomb. Any of these flashpoints could ignite at any time in Trump’s first 100 days.

European governments want to present a strong, united front. But Trump seems more interested in buying Russia off by acquiescing in Putin’s reclamation of former cold war spheres of influence. Trump’s disdain for the EU – he loudly applauded Britain’s vote to leave – and critical European reaction to his election, notably in Germany and France, point to a possible US-Europe schism down the road. If it happens, Trump will have helped Putin achieve a long-cherished Russian strategic objective, shattering 70 years of Euro-Atlanticism.

CHINA

Beijing shows no sign of backing away from its expansionist policies in the South China and East China seas. It is busily transforming reefs and tiny islands into military bases, which will ultimately give it control of sea lanes through which much of the world’s maritime trade passes. China continues to ignore the rival territorial claims of neighbouring countries, including Japan, whose commerce is directly threatened.

To counter China, the US and Japan have stepped up naval and air patrols in the disputed areas. They have also pursued closer military cooperation with Vietnam and other regional states such as Australia. A recent UN court ruling in the Hague on a complaint brought by the Philippines rejected China’s claims as illegal. But Beijing rejected the decision, and has since sought to woo the Philippines’ anti-American president, Rodrigo Duterte.

It is more than likely, on present trends, that the US and Chinese militaries will, sooner or later, come into direct confrontation, either by air or at sea. Until now a clash has been avoided, partly because neither side knows where it would lead. Nationalist feeling in China is periodically whipped up by the Communist party. If Trump blunders into this delicate situation, or deliberately tries to push the Chinese back, the fallout could be dangerous.

In terms of tripwires, Taiwan is, as always, a trap for an unwary American leader. Taiwan elected a new president earlier this year whom the Chinese suspect of pursuing an independence agenda. It has since increased pressure on Taipei, including suspending talks. Taiwan has been a frozen conflict for so long that it is hard to imagine it suddenly going “live”. But Xi Jinping, China’s hard-headed president, is clear that he will not wait indefinitely for reunification. Like Trump, he is used to getting what he wants.

NORTH KOREA AND IRAN

The issue of nuclear proliferation links these two countries. Iran has always denied possessing or trying to acquire or build nuclear weapons in the past. Last year’s landmark pact between Washington, its European partners and Tehran produced pledges that Iran would not seek to make a bomb in the future, or at least for the next 10 years.

But Trump is on record as saying the deal is a bad one and should be scrapped. This stance plays into the hands of hardline clerics in Tehran who have consistently opposed president Hassan Rouhani’s policy of nuclear concessions in return for UN sanctions relief. Israel’s right-wing government, led by Benjamin Netanyahu, Trump’s new best friend (see below), also wants the deal scrapped. If Trump reneges, Rouhani will be undermined, as will be global counter-proliferation efforts.

North Korea’s dictator, Kim Jong-un, not only already has nuclear weapons, but is accelerating and expanding the country’s weapons-building programmes, much to the alarm of Japan, South Korea and the west. In the past, Trump suggested he might meet Kim. The offer was laughed off in Pyongyang. A parlay between Kim and Trump might set some kind of record for clashing egos. But it would be unlikely to achieve much.

Trump’s other suggestion, that Japan and South Korea acquire nuclear weapons to deter North Korea, was one of his more irresponsible – and insensitive, given Japan’s unique experience in 1945. North Korea will be watching the Trump administration closely. If it senses Trump is distracted, or disinterested in Asian security issues (which has certainly appeared to be the case until now), Kim could try something provocative or risky, if only to test US reactions. Given that he is three-parts unhinged, that is a scary prospect.

ISRAEL AND PALESTINE

Donald Trump with Israel’s Benjamin Netanyahu in New York. Photograph: Reuters

Trump has taken a staunchly pro-Israel line since running for president and has promised to be the country’s “closest friend”. What this may mean in practice is the subject of speculation. But Trump advisers have told Israeli media that one of his first acts will be to order the removal of the US embassy in Tel Aviv to Jerusalem.

Such a decision, resisted by past Democrat and Republican presidents alike, is of enormous symbolic importance since it would represent de facto recognition of Israel’s claim to all of Jerusalem as its indivisible capital. It would negate, in one sweeping gesture, the Palestinians’ claim to east Jerusalem as the capital of a future independent Palestinian state.

Benjamin Netanyahu, Israel’s prime minister, has been careful to keep on the right side of Trump, having fallen out with Barack Obama over US peacemaking efforts and a range of other issues. Netanyahu’s obsequiousness may be paying off. As far as is known, he is the first foreign leader to be invited to the Trump White House. Some of his more hardline cabinet ministers are meanwhile predicting the end of any American efforts to implement a two-state solution.

The Palestinian leadership has politely congratulated Trump on his success. But if he makes the Jerusalem switch, anger in the occupied territories and Gaza will be intense, and could quickly turn violent. Another intifada is the very last thing the Middle East needs. But as the world now knows, uprisings are a Trump speciality.