F-35 jets: US military grounds entire fleet
The US military has temporarily grounded its entire fleet of F-35 fighter jets in the wake of a crash in South Carolina last month.
Inspections are to be carried out on faulty fuel tubes.
An official report questioned earlier this year whether the F-35 was ready for combat after dozens of faults were found.
The F-35 is the largest and most expensive weapons programme of its type in the world.
The programme is expected to last several decades and global sales are projected to be 3,000. The US government's accountability office estimates all costs associated with the project will amount to one trillion dollars.
In a statement, the F-35 Joint Program Office said the US and its international partners had suspended flight operations while a fleet-wide inspection of fuel tubes was conducted.
"If suspect fuel tubes are installed, the part will be removed and replaced. If known good fuel tubes are already installed, then those aircraft will be returned to flight status.
"Inspections are expected to be completed within the next 24 to 48 hours."
The aircraft, which uses stealth technology to reduce its visibility to radar, comes in three variants.
The crash in South Carolina involved an F-35B , which is able to land vertically and costs around $100m (£75m).
The pilot in that incident ejected safely but the aircraft was destroyed.
The plane, manufactured by Lockheed Martin but including parts made in several other countries, has been sold to a number of nations, including the UK, Japan, Italy, Turkey and South Korea.
The Ministry of Defence in London said the UK had decided to "pause some F-35 flying as a precautionary measure while we consider the findings of an ongoing enquiry".
But the MOD said F-35 flight trials from the aircraft carrier, HMS Queen Elizabeth, were continuing and the programme remained on schedule to provide UK armed forces with "a game-changing capability".
No going back
By Jonathan Marcus, Defence and Diplomatic Correspondent
The temporary suspension of all F-35 flights is an embarrassment given the extraordinary cost of this frequently troubled programme. But the problem has already been identified as faulty fuel tubes. Once these are checked or replaced the aircraft will be back in the air.
The F-35 is only just entering service but it is already the most expensive weapons programme of all time.
It will equip the US Air Force and Marine Corps as well as several of Washington's allies. It represents a step-change in capability but the F-35's complexity has inevitably thrown up problems.
However there is no going back now. It promises to be the centrepiece of US air power for decades to come.
While its costs per aircraft are coming down there are still questions about how many planes the US can afford and whether it should also buy a cheaper, less capable aircraft alongside the F-35.
The F-35, first used in combat by Israel earlier this year to carry out two strikes, is designed for use by the US Air Force, Marine Corps and Navy.
It boasts avionics, sensors and communications that allow data to be shared quickly with operational commanders.