President Muhammadu Buhari has said that he gave approval for withdrawal of $462 million from the Excess Crude Account (ECA) because he believed the National Assembly would have no objection to his action.
The action being referred to by the president is the purpose of the fund: procurement of 12 Super Tucano aircraft from the United States.
Mr Buhari's explanation was conveyed in a letter read at the Senate on Wednesday. A copy of the letter had earlier been sent to the House of Representatives.
First, Mr Buhari explained the processes that led to the approval.
"I wish to draw the attention of the Senate to the ongoing security emergencies in the nation. These challenges were discussed with the state governors and subsequently at the meeting ot the National Economic Council on the 14th of December 2017 where a resolution was passed with the council approving that up to $1 billion may be released and utilised from the Excess Crude Account to address the situation.
"Subsequent upon this approval, we are preparing a comprehensive schedule of all the requirements for each of the security services for presentation to the National Assembly for consideration.
"It would be recalled that, for a number of years, Nigeria had been in discussions with the United States Government for the purchase of Super Tucano Aircraft under a direct Government-to-Government arrangement. Recently, approval was finally granted by the United States Government, but with a deadline within which part payment must be made otherwise, the contract would lapse."
Mr Buhari said he was confident the National Assembly would approve release of the fund, hence his anticipatory approval.
"In the expectation that the National Assembly would have no objection to the purchase of this highly specialised aircraft, which is critical to national security, I granted anticipatory approval for the release of US$496,374,470.00. This was paid directly to the treasury of the United States Government.
"I am therefore writing, seeking approval of this House for the sum of US$496,374,470.00 (equivalent to N151, 394, 421, 335. 00) to be included in the 2018 Appropriation Bill, which the National Assembly is currently finalising. The balance of the requirements for critical operational equipment is still being collated from the different security services and will be presented in the form of a Supplementary Appropriation Bill, in due course.
"The Honourable Minister of Defence and other appropriate officers will be available to provide further details, as may be required."
"While thanking the Senate for the usual cooperation, please be assured Mr. Speaker, the assurance of my highest regards."