Energy: Mexico's state oil firm, our second-largest foreign supplier, is under attack from drug cartels. But that's not stopping the U.S. from investing more in its operations while American rigs lie idle in the Gulf. The volatile Middle East is often seen as the nexus of risk to U.S. energy supplies. But the biggest threat may be next door, in Mexico. It's bad enough that oil production there is declining due to underinvestment. But now the state oil monopoly, Pemex, is encountering a threat no one foresaw a few years ago: attacks from the country's notorious criminal cartels. The Los...