Israel says it has carried out air strikes with the F-35, in what would be a world first.
Israel says it has become the first country in the world to carry out combat air strikes with the new F-35 stealth fighter, the advanced warplane that will soon be used by air forces around the globe.
"We have performed the first operational F-35 strike in the world. We attacked twice in the Middle East using the F-35," Major General Amikam Norkin, the head of the Israeli Air Force, said in a briefing to foreign air force officers.
Norkin did not say where the F-35s had been used, but Israel has carried out repeated strikes in Syria in the past three years. It has also hit Hizbollah targets in southern Lebanon.
Norkin showed the foreign officers a photograph of an Israeli F-35 over Beirut, in what was widely seen as a warning to Hizbollah about Israel's ability to carry out strikes in Lebanon.
The Jerusalem Post reported that with "an extremely low radar signature, the F-35 is able to operate undetected deep inside enemy territory, such as Iran, as well as evade advanced missile defense systems like the advanced Russian-made S-300 and S-400".
Israel's Prime Minister Benjamin Netanyahu was a strong advocate for US President Donald Trump pulling out of the international deal with Iran over its nuclear programme.
Israel so far has nine of the warplanes. Under a military aid agreement with the US, it purchased 19 F-35s at US$125 million ($180m) per plane. A further 14 jets cost US$112m each.
The F-35s are being produced primarily for the US military but they will eventually be used by armed forces across the globe, including in Britain, Australia and Japan. The UK has committed to purchasing 138, and has so far bought 48 jets at a cost of £9.1 billion. The British Government is reconsidering its pledge to purchase the remaining 90 American stealth fighters because of their vast cost, at £190m ($368m) a unit. The Ministry of Defence is reportedly thinking of buying European-made Eurofighter Typhoons, which are roughly half the cost.
A decision to go back on the F-35 purchases could spark a major row between the UK and the Trump Administration.
Meanwhile, Russia has denied claims that its new nuclear-powered cruise missile crashed repeatedly during testing and flew only 22 miles. The missile was one of a range of "invincible" nuclear weapons unveiled by President Vladimir Putin in March. Sources told CNBC that four tests of the missile between last November and February all ended in crashes.