The F-35 Joint Strike Fighter (JSF) system development and demonstration (SDD) phase may have an additional year added to it, according to a newly-released Dutch military document.

A letter by the Dutch military chief to Parliament, dated 7 May, says JSF programme executives are considering the one-year extension.

A "final decision" to extend the SDD would probably be made by "autumn 2008". Parliament would be informed on the consequences of such an extension at a later date. The document also mentions that the Dutch Initial Operation Test and Evaluation phase would be extended if SDD is also extended.

Programme officials revealed the new schedule proposals during a meeting of the JSF Executive Steering Board (JESB) in Amsterdam on 22 April.

The agenda covered by the JESB involves every aspect of the program.

The JESB meets twice a year, in spring and in autumn. The presidency of the JESB is shared by the United States and a partner. Every third meeting is held in the country of the co-chairman after which the co-presidency passes to another partner.

The Netherlands was designated as a co-chairperson the JESB this past April in Amsterdam. The next co-chairmanship will be handed over to the United Kingdom.

The impact of extending the SDD phase by one year on the overall programme was not immediately clear

The US-based JSF joint programme office did not immediately return phone calls seeking comment.

Also unknown are the reasons for the potential extension of the SDD phase. A recent critical report published by the US Government Accountability Office (GAO) claimed delays were likely for several reasons, including slow progress on manufacturing.

But Lockheed and JSF programme officials countered that the program is relatively healthy and running under cost.