The government said Saturday it will update its F-15 fighter fleet or buy more F-2s, given the delay in development of the F-35, which it hopes will be the next mainstay fighter.

Either option, however, is expected to pose headaches for defense officials, while the government could face criticism that in the interim the nation is letting its guard down.

In 2004, the Cabinet endorsed a five-year defense buildup plan through 2009 that included procurement of seven next-generation fighters to succeed the F-4s that are set to be retired in this decade.