Adherence to an unsustainable currency union - the Gold Standard - then forced governments to continue deflation-worsening policies, provoking social unrest and inter-country tension over unpaid debts (in this case war reparations, but still debts).

BBC: Thinking outside the 1930s box

Although it probably seems unthinkable today, there was a time when countries would actually go to war and seize territory over debts.

FORBES: How Debt Limits A Country's Options

Nations felt pressure to quickly repay debts accumulated during the war, but higher interest rates led to lower economic output, which in turn led to more protectionism.

FORBES: How Debt Limits A Country's Options

The IMF retorts that it might take 20 years for Europe to pay off the government debt built up during the 2008 financial crisis, global recession, and recovery, recalling that it took that long to pay off the debts Europe ran up during World War II without unduly creating hardships on the population.

FORBES: Feeling That European Springtime Swoon Coming On Again

Most countries hope eventually to outgrow their debts - that is what happened with the debts run up by the UK and US to finance World War II.

BBC: Budget 2013: Radical options for the UK economy

America may find it has to promise that the new Iraq will honour those debts and that, even if old oil contracts are not honoured, opponents of the war will not be excluded from new contracts.

ECONOMIST: Who will run the new Iraq? | The