Nigerian President Umaru Yar'Adua has changed his chief of defence staff and installed new figures at the head of the army, navy and air force, dpa reported.
Air Marshal Paul Dike becomes new Chief of Defence Staff, Major General AB Dambazau took over as the head of the army and Rear Admiral Isaiah Ibrahim became chief of the navy.
Air Marshal Oluseyi Petinrin took over from Dike as the head of the air force.
All of the men being replaced were due for retirement, the president's office said.
Yar'Adua took office over a year ago and is under pressure to quell unrest in the oil-producing Niger Delta region, where militants have been attacking oil facilities and kidnapping workers.
The attacks have cut Nigeria's oil output by around 20 per cent since 2006 and helped push up global oil prices.