ARGENTINA’S INVASION of the Falkland Islands, which began 30 years ago Monday, was a monumental blunder that led to war with Britain and the death of some 650 Argentine and 255 British servicemen. Yet the conflict did the perpetually unstable South American country some good. It caused the collapse of a brutal military dictatorship and, as it turned out, broke a long history of military interventions in politics. For the past three decades, Argentina has been a democracy.

Proof that the maladies of Argentine politics have not been cured, however, can be found in the latest Falklands campaign ginned up by the government of President Cristina Fernández. To its credit, Ms. Fernández’s government has not only sworn off the use of military force in the Falklands but cut military spending so sharply that it’s doubtful Argentina could mount another invasion. But like the military junta of 1982, it seeks to distract attention from a host of domestic ills by catering to the curious jingoism provoked by the island chain, which Argentina calls the Malvinas. In pursuit of its demand that Britain open negotiations on sovereignty, it has begun turning away ships from the Falklands and cutting back on British imports; it’s also pressuring Chile to cut off the sole air link from South America to the islands.

The Argentine cause, which has been drummed into schoolchildren for generations, is odd because Argentina has no modern connection or claim to the windswept islands other than relative geographical proximity. They are about 300 miles from the southern Argentine coast, but Britain has controlled them since 1833. Their some 3,000 inhabitants overwhelmingly wish to remain British, which means that Argentine demands for “decolonization” are at odds with the principle of self-determination. Though it toyed with the idea of handing over the Falklands before the war, Britain now is firmly committed to the Falklanders’ rights, and it spends about $300 million annually on their defense. The Obama administration, which unsettled London by supporting the idea of negotiations two years ago, has wisely refrained from pushing that position.

More than in 1982, Argentina has pragmatic reason for its lust for the Falklands: Oil has been found off the coast. Yet the best way for Ms. Fernández to pursue those interests would be to pursue something like the opposite of her current policy. Were Buenos Aires to cultivate economic and travel links to the Falklands, as it did before 1982, it could become a supplier of the growing economy there; if residents could visit and study in Argentina, they might grow more fond of the place. Better yet, Argentina could begin to attract investors to explore its own coastal waters for oil and develop its substantial shale deposits on land.

As it is, Ms. Fernández’s pointless drumbeating only reminds foreign investors of why they steer clear of Argentina. Though generals may no longer bait rabid crowds from the balcony of the presidential palace, the vacuous populism that has hamstrung a potentially rich country lives on.