Passage: Its foreign policy closely follows that of its main ally, France (one of its former colonial rulers). Cameroon relies heavily on France for its defence, although military spending is high in comparison to other sectors of government.President Biya has engaged in a decades-long clash with the government of Nigeria over possession of the oil-rich Bakassi peninsula. Cameroon and Nigeria share a 1,000-mile (1 600 km) border and have disputed the sovereignty of the Bakassi peninsula. In 1994 Cameroon petitioned the International Court of Justice to resolve the dispute. The two countries attempted to establish a cease-fire in 1996, however, fighting continued for years. In 2002, the ICJ ruled that the Anglo-German Agreement of 1913 gave sovereignty to Cameroon. The ruling called for a withdrawal by both countries and denied the request by Cameroon for compensation due to Nigeria's long-term occupation. By 2004, Nigeria had failed to meet the deadline to handover the peninsula. A UN-mediated summit in June 2006 facilitated an agreement for Nigeria to withdraw from the region and both leaders signed the Greentree Agreement. The withdrawal and handover of control was completed by August 2006.

Question: Who is Cameroon's main ally?
France