WARRI, Nigeria (AP) — The Nigerian Navy said it has destroyed 260 illegal oil refineries and burned 100,000 tons of contraband fuel, but critics say this targeting of small-time criminals fails to confront the biggest culprits in oil thefts — the politically-connected criminal cartels who sell on the international market.

Similar missions in the past have failed to slow thefts valued at more than $20 million a day on the world market. Shell Nigeria, the biggest operator in the West African nation, said it lost $1 billion to oil thefts in 2013.