Vladimir Putin is not short of problems, many of his own creation. There is the carnage in eastern Ukraine, where he is continuing to stir things up.

There are his fraught relations with the West, with even Germany turning against him now. There is an Islamist insurgency on his borders and at home there is grumbling among the growing numbers who doubt the wisdom of his Ukraine policy.

But one problem could yet eclipse all these: Russia’s wounded economy could fall into a crisis.

Some of Russia’s ailments are well known. Its oil-fired economy surged upward on rising energy prices; now that oil has tumbled, from an average of almost $110 a barrel in the first half of the year to below $80, Russia is hurting.

More than two-thirds of exports come from energy. The rouble has fallen by 23% in three months. Western sanctions have also caused pain, as bankers have applied the restrictions not just to Mr Putin’s cronies, but to a much longer tally of Russian businesses. More generally, years of kleptocracy have had a corrosive effect on the place. Much of the country’s wealth has been divided among Mr Putin’s friends.

Russian President Vladimir Putin (L) and billionaire Arkady Rotenberg (R) attend the funeral of his former judo trainer Anatoly Rakhlin on August 9, 2013 in Saint Petersburg, Russia Sasha Mordovets/Getty Images Everybody expects continued stagnation, but the conventional wisdom is that Mr Putin is strong enough to withstand this. The falling rouble has made some export industries like farming more competitive. These exports combined with Mr Putin’s import-blocking counter-sanctions mean Russia still has a small trade surplus. It has a stash of foreign-exchange reserves, some $370 billion according to the central bank’s figures.

Add in the resilience of the Russian people, who are also inclined to blame deprivation on foreigners, and the view from Moscow is that Mr Putin has time to manoeuvre. People talk loosely about two years or so.

In fact, a crisis could happen a lot sooner. Russia’s defences are weaker than they first appear and they could be tested by any one of a succession of possibilities—another dip in the oil price, a bungled debt rescheduling by Russian firms, further Western sanctions. When economies are on an unsustainable course, international finance often acts as a fast-forward button, pushing countries over the edge more quickly than politicians or investors expect.

Putin a good man down

The immediate worry is the oil price. Mr Putin is confident it will recover. But supply seems set to increase, with OPEC keen to defend its market share. American government agencies predict oil prices could average $83 a barrel in 2015, well below the $90 level Russia needs to avoid recession (and to keep its budget in balance). If global demand weakens—Japan has slipped into recession since the latest round of forecasts—the oil price could fall further. That would immediately prompt investors to reassess Russia’s prospects.

President of Russia Vladimir Putin (L) and Crown Prince Salman bin Abdulaziz Al Saud (R) of Saudi Arabia talk through their interpreters during a plenary session at the G20 leaders summit in Brisbane November 15, 2014. Rob Griffith/Reuters Then there are the debt repayments. Russia’s firms have over $500 billion in external debt outstanding, with $130 billion of it payable before the end of 2015, at a time when few Western banks want to increase their exposure to Russia. Even firms that earn dollar revenues may struggle to pay their debts.

Rosneft, an oil giant, recently asked the Kremlin to lend it $44 billion. Mr Putin has so far resisted, but he cannot let a company that is 70% state-owned and employs 160,000 people fail. There is a lengthening queue of troubled Russian firms. Non-performing loans were rising even before interest rates were raised to 9.5% to defend the rouble. Meanwhile Russian banks are reliant on the central bank to replace deposits that their customers are understandably spiriting into dollars.

Directly or indirectly, many of these bills will end up with the Kremlin, which is why its reserves will be vital. They are evaporating: down $100 billion in the past year, following failed attempts to defend the rouble. And the book-keeping is dodgy.

An employee prepares a train loaded with gasoline at the Petrolchemie and Kraftstoffe (PCK) oil refinary in Schwedt/Oder, October 20, 2014. Axel Schmidt/Reuters Of the reported $370 billion reserve pile, more than $170 billion sits in the country’s two wealth funds. Some of their assets are iffy, including various stakes in Russia’s state-owned banks and debt issued by Ukraine that Mr Putin’s own aggression is fast rendering worthless. One of the funds is earmarked for pensions.

In reality, Russia’s government has perhaps $270 billion of hard cash that is accessible and usable without massive cuts elsewhere—less than its external obligations due over the next two years.

An artwork depicting a portrait of Russian President Vladimir Putin based on a layer of U.S. dollars and Russian roubles. Ilya Naymushin/Reuters/Amanda Macias/Business Insider All this spells trouble for Russia, but Mr Putin’s marauding foreign policy could accelerate things.

This after all is a man who has invaded other countries and lied about it.

A deeper foray into Ukraine would lead to stronger sanctions by Western countries. Some of them, such as barring Russia’s banks from the SWIFT international payments system (see article), could halt Russian trade altogether.

A partial block on oil exports would fell the economy, as it did Iran’s. And the more trouble he faces, the more likely Mr Putin is to play the nationalist card—and that means more foreign forays, and yet more sanctions.

From Russia to Rio, without much love

Russia’s biggest recent economic crisis, in 1998, led to a government default. This time a string of bank failures, corporate defaults and a deep recession look likelier.

Brazil's President Dilma Rousseff (L) talks with Russian President Vladimir Putin before the 6th BRICS summit in Fortaleza July 15, 2014. Nacho Doce/Reuters Even so the pain from these could spread abroad quickly, both to countries that rely on Russian trade (exports to Russia account for fully 5% of GDP in the Baltics and Belarus) and through financial ripple effects. Banks in both Austria and Sweden are exposed. And if firms in one badly run commodity-driven country start to default on their dollar debts, then investors will worry about others—such as Brazil.

If Russia’s economy looks likely to collapse, there will be inevitable calls in the West for sanctions to be cut back. This week Mr Putin pointed out that 300,000 German jobs depend on trade with his country. But Angela Merkel rightly stood firm.

Actions, Mr Putin must finally learn, have consequences. Invade another country, and the world will act against you. And the same goes for the economy, too. Had Mr Putin spent more of his time strengthening Russia’s economy than enriching his friends, he would not find himself so vulnerable now.

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