The US Air Force chief of staff Gen. Norton Schwartz said the US will slow the testing and acquisition of the F-35 joint strike fighter.
Schwartz said the US now wants to lengthen the period of testing, increase the number of test assets and reduce production rate in relation to the JSF programme, according to defensenews.com.
"The F-35 will be ready for initial operational capability with the air force in 2013," he said.
The US will make some adjustments to the F-35 to ensure that fighters are problem-free following its delivery to its buyers.
The JSF development and acquisition programme is designed to replace a wide range of aging fighter, strike, and ground attack aircraft for the US and its allies.
A fifth-generation fighter, the F-35 has a single-seat and a single-engine, and can perform close air support, tactical bombing and air defence missions.