The UK's new F-35B Lightning II stealth fighter jets have joined the fight against the Islamic State group in their first operational missions.
The jets, based in Cyprus, have carried out more than 14 armed reconnaissance missions over Iraq and Syria, the Ministry of Defence says.
The RAF said the F-35s had not carried out any attacks and that the operations had gone "exceptionally well".
Defence Secretary Penny Mordaunt called it "a really historic moment".
Britain currently has 17 F-35Bs and has pledged to purchase 138 in total from US aviation giant Lockheed Martin.
The aircraft - which cost almost £100m - can land vertically, similar to the Harrier Jump Jet, and combine radar-evading stealth technology with supersonic speeds.
Six of the jets have been deployed at RAF Akrotiri in Cyprus since May for training exercises, in an operation known as Exercise Lightning Dawn.
As part of their training, the jets carried out 95 missions and flew in pairs for 225 hours, the MoD said.
They have now joined the hunt for militants under Operation Shader, the UK's contribution in the ongoing military action against IS.
Speaking from the Cypriot RAF base, Ms Mordaunt said she was "very proud that these are now flying in defence".
She added: "It obviously has some incredible capabilities which are really putting us in the lead."
The jets, jointly operated by the RAF and the Royal Navy, are expected to take off from the decks of the new £3.1bn Queen Elizabeth Class aircraft carrier in the autumn for more testing.
Why F-35 jets' real test is still to come
By BBC defence correspondent Jonathan Beale
The first of Britain's most advanced and expensive fighter jets have now carried out more than a dozen missions over Iraq and Syria.
With IS having lost its territory and on the run there are now few obvious targets.
The F-35s have not yet conducted any airstrikes. Instead they've been using their sophisticated sensors to gather intelligence.
The RAF describes the F-35 as the best "eyes and ears" on the battlefield, even though the jet is still suffering from a host of technical problems.
But its other great asset is that it is hard to see. Britain's first "stealth" jet can, in theory, avoid detection by enemy radar.
The real test in combat will not be against the remnants of IS, but a well armed opponent with advanced air defences.