While he is just 44, he has long experience in the extraction side of the energy business, building public-private teams to maximize production for state-owned oil companies. He quit YPF SA after Repsol took over in 1999, and then rose through the ranks of Houston, Texas-based oil services giant Schlumberger Inc., helping to turn failing projects into moneymakers in Mexico and Indonesia.

Kicillof, 41, is the political side of the equation. While he's just a deputy economy minister and officially her second-ranking representative in the YPF intervention, the expropriation was essentially his project from the start. He helped draft the law, which ignores a constitutional requirement to pay in advance for expropriations, and strongly argued that Spain's Repsol shouldn't get anywhere near the $10.5 billion it has demanded in compensation.

An economist who has published two books on the theories of John Maynard Keynes, Kicillof believes government must make sure private industry operates in concert with a country's priorities, taming markets and protecting consumers and workers.