The immediate past service chiefs have appeared before the senate committee on foreign affairs for screening as ambassadors of Nigeria.
President Muhammadu Buhari appointed them as ambassadors after they left office in January.
The ex-service chiefs are Abayomi Olonisakin, former chief of defence staff; Tukur Buratai, former chief of army staff; Ibok-Ete Ibas, former chief of naval staff, and Sadique Abubakar, chief of air staff.
Mohammed Usman, a former defence chief, was also appointed as an envoy by the president.
Some Nigerians criticised the nominations owing to the performance of the ex-service chiefs on security in the north-east and in the country.
But the presidency defended their appointment, saying it is a reward for hard work.
“The President is rewarding hard work and exceptional sacrifice by a set of military leaders who gave their best to the nation and will be remembered, sooner than later, for their contributions to the security and survival of Nigeria as one nation,” Garba Shehu, presidential spokesman, had said in a statement.
“They should be allowed to move to the next level. This is so that their examples will help to inspire others if given the opportunity to serve and this transition is normal in decent democratic societies.
“How on earth can decent people run down hardworking professionals who have put in their best to defend their country?”