Sometimes the most obvious and tempting strategy is the stupidest. That applies to Argentina’s decision to seize a majority share in YPF, its biggest oil company, from Repsol, the Spanish energy group.

It is obvious because Latin American countries have often expropriated the assets of foreign companies, ever since Bolivia did so to Standard Oil in 1937. It is tempting for President Cristina Fernández because oil is expensive, confidence in her erratic government is low and Repsol is a soft target.

But it is stupid because Ms Fernández has her tactics wrong. The best time to squeeze foreign companies is when the hard work of investment and exploration is over and a state-owned oil company can reap the benefits. It is not when your country has deep fiscal problems, no access to international capital markets and a looming investment challenge.