Hubris begets nemesis, as the ancient Greeks opined. It’s a life lesson Recep Tayyip Erdoğan, Turkey’s arrogant leader, appears unable to absorb as his country teeters over an abyss of his making. Erdoğan argued in June’s elections that an all-powerful executive presidency was the best way to govern – and he was the best man for the job. His wish was granted. Now Turkey is in crisis. The fall from grace – this shattering of the omnipotent strongman-sun king image – has come more quickly than anybody imagined. And since Erdoğan is in sole charge these days, he will be hard put to avoid sole blame.

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The immediate focus of this very Turkish tragedy is the collapse of the lira, down 40% or more against the dollar. This reflects wider debt and inflation problems, which Erdoğan has failed to tackle. In truth, he called the elections early because he feared rising prices and growing shortages of food staples could undermine his chances. The resulting lack of confidence in Turkey’s economic management and fears of a default have now infected global markets, adversely affecting lender banks, the value of the euro, and developing economies from Asia to Africa.

This turmoil is about far more than the price of onions in Istanbul. Turkey’s many troubles have wide geopolitical and strategic ramifications. The country is, as ever, awkwardly positioned between two ostensibly friendly but imperious powers: the US and Russia. Since taking national office in 2003, Erdoğan has tried to play them off against each other, with mixed success. Now the many contradictions in his policy positions are coming to a head, with unpredictable implications for Syria, Iran, Nato and already strained relations with Europe.

The overall picture is of a faltering regional power being squeezed between a rock and several hard places, the commentator Yavuz Baydar suggested on the Turkish news platform Ahval: “Ankara is in a diplomatic cul-de-sac. It is at odds with the US in the region and now faces a moment of reckoning vis-a-vis Russia. Meanwhile, the Kurds remain a reality near and within Turkey’s borders; a deepening economic crisis makes it increasingly vulnerable; and its erratic regional policy makes it difficult to pursue any dialogue that requires trust and steadfastness.”

While Erdoğan cannot escape political responsibility, he is nevertheless trying hard to do so. He blames a foreign conspiracy for the lira meltdown. “What is the reason for all this storm in a teacup? There is no economic reason ... This is called carrying out an operation against Turkey,” he told supporters in Trabzon. The US, he said, had stabbed Turkey in the back. Here was his usual offering of denial and defiance. Erdoğan habitually relies on a mix of nationalism, faith and fear of foreigners to deflect criticism. “If they have dollars, we have our people, our righteousness and our God,” he said last week.

Who can save Turkey from itself? The question is incorrectly framed. It really should be: who can save Turkey from Erdoğan?

The president’s fierce grip on power is such that he is unlikely to be dislodged soon. The army, responsible for a failed coup in 2016, has been purged. So, too, have other centres of possible opposition. Parliament has been reduced to a toothless talking shop. Erdoğan’s mistakes, including his refusal to raise interest rates to cool the overheating economy and his unashamedly nepotistic appointment of his son-in-law as finance minister, thus go uncorrected. There will be no U-turns. His self-righteous stubbornness is Thatcheresque.

All of which suggests Turkey’s problems will get worse before they get better.

In Donald Trump, Erdoğan faces a wilful egotist of similarly unbending disposition. The two have clashed over Turkey’s unjustified jailing of an American pastor on terrorism charges. Its decision to prolong Andrew Brunson’s detention personally irked Trump. Last week’s sudden imposition of sweeping US tariffs on steel and aluminium imports was one response. It intensified pressure on Ankara at a critical moment, no doubt deliberately.

But the US and Turkey have long been at odds over more weighty matters such as Syria, where Erdoğan has seized territory, ostensibly to contain the threat posed by Kurdish militias (whom he regards as terrorists). Latest reports say the Turkish army is encouraging the formation of a new force of non-Kurdish Syrian rebel factions with a view to creating a permanent border buffer zone. Naturally, this is opposed by Bashar al-Assad’s regime in Damascus. The US, informally allied to Kurdish forces, is not keen on the idea, either.

Add to this past threats to attack US special forces in northern Syria and Iraq, his rejection of Trump’s sanctions on Iran and subservience towards Israel, Turkey’s opaque links to Islamist groups, its limiting of airbase facilities available to Nato forces fighting Islamic State and its purchase of advanced Russian-made missiles, and it is not hard to see why bilateral relations are on edge. Talks last week failed to bridge the gaps. When Erdoğan himself went to Washington last year, his thuggish bodyguards assaulted protesters and local police – an incident that understandably caused lasting anger.

Reflecting the depth of antagonism towards Erdoğan, in June members of Congress urged the Pentagon not to sell Turkey F-35 fighters, arguing that: “Contrary to its Nato obligations, Turkey is actively operating to undermine US interests around the world. Turkey’s repeated military actions against American interests, relentless degradation of human rights and democracy under Erdoğan, and its clear intention to build a strategic partnership with Russia, have completely eroded the US-Turkey relationship.”

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The EU is equally concerned, notably over Erdoğan’s serial abuses of human rights and his commitment to an agreement stemming Syrian refugee flows into Europe. Worries also persist about his approach to divided Cyprus and the disputed energy fields of the eastern Mediterranean, and his hostility towards regional allies such as Greece, Israel and Egypt. As with the US, his threats to abandon Nato and seek new allies in Moscow and Beijing have raised toxicity levels. All these problems could easily get worse.

And yet, in a rarely matched piece of geo-strategic incompetence, Erdoğan is now in danger of simultaneously alienating Vladimir Putin. The issue is Idlib, the north-western Syrian province that is the last refuge of anti-Assad forces and a haven for 2.5 million internally displaced people. Putin wants Turkish support for the expected autumn offensive by Syrian, Iranian and Russian forces. Turkey fears another cross-border exodus of refugees. Erdoğan is also sticking to his buffer-zone idea. The result: a standoff that further underscores Turkey’s international isolation and the sense of developing crisis.

Besieged on all sides and failing internally – who can save Turkey from itself? The question is incorrectly framed. It really should be: who can save Turkey from Erdoğan? The answer: only Turks. But it’s going to take a while and will be a rough ride, and the accompanying domestic and international turmoil will be considerable. Like Icarus, Turkey’s hubristic, highly combustible sun king has a long way to fall.

• Simon Tisdall is a foreign affairs commentator