A report published in the Nigerian newspaper Wednesday said that the U.S. Navy was patrolling the Gulf of Guinea, home to Nigeria's biggest oil field, Bonga Project, to prevent the field from being targeted "by terrorists and other maritime criminals."

Adm Harry Ulrich, commander of U.S. Naval Forces in Europe and Africa, told The Guardian: "We hear a series of stories for our presence in the Gulf of Guinea, but I want to say that we are concerned for Nigeria and we want to help her protect the region from the hands of maritime criminals.

"In all parts of the world, the U.S. and any good nation want safe coasts for those countries who are supplying our/their energy, and that is why we are often there. So there is nothing to fear for Nigeria."

There had been fears that the ships were in place for military purposes, but Ulrich, speaking at the Seapower for Africa symposium in Abuja, said that though the Nigerian federal government was trying to secure the area, the U.S. ships were in the region as a result of their concern for Nigeria, and their dependence on its oil.