FILE PHOTO: An Israeli Air Force F-35 fighter jet flies during an aerial demonstration at a graduation ceremony for Israeli Air Force pilots at the Hatzerim air base in southern Israel, December 27, 2017. REUTERS/Amir Cohen

JERUSALEM (Reuters) - Israel’s military said on Thursday it was testing its fleet of F-35 fighters after receiving findings from U.S. investigators that a different model of the plane had a fuel systems flaw.

The military, on Twitter, stopped short of saying the Israeli F-35s had been grounded, describing them as remaining on operational standby.

A Pentagon spokesperson said earlier Thursday that all U.S. and international F-35 fighter jets made by Lockheed Martin Co had been grounded so that fuel tubes can be examined.

Israel’s military said its air force chief “decided to exercise extreme caution” and test all the F-35s, “even though this was not the model used by the Israeli Air Force and that no failures have been found in the planes.”

It said it expected the examination to last a few days, after which the F-35s would return to full operation.