The country will purchase 12 nuclear weapon-capable F-35A fighters, in the "biggest strengthening of the UK's nuclear posture in a generation", Downing Street said, adding Starmer would announce the plan at a NATO summit Wednesday.

"These F35 dual capable aircraft will herald a new era for our world-leading Royal Air Force and deter hostile threats that threaten the UK and our Allies," Starmer said in a statement.

NATO Secretary General Mark Rutte was quoted in the statement as saying: "I strongly welcome today's announcement," calling it "yet another robust British contribution to NATO".

Since the end of the Cold War, British nuclear deterrence within the Atlantic alliance was provided solely by missiles aboard Royal Navy submarines.

At that time, "there was no longer any real interest in tactical nuclear weapons in Europe, because the threat had disappeared," Heloise Fayet, a nuclear specialist at the French Institute of International Relations (Ifri), told AFP.

She said Tuesday's announcement illustrates "the continued re-nuclearization of Europe, the renewed need for nuclear weapons, and the strengthening of NATO's deterrence, in the face of an adversary, Russia", which has been at war with Ukraine for three years.

The F-35A, manufactured by US company Lockheed Martin, is a variant of the F-35B already used by the United Kingdom, but which can carry nuclear warheads in addition to conventional weapons.

The acquisition has been a long-standing request from the Royal Air Force.

The planes are expected to be stationed at Marham Air Force Base in eastern England.

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LOCKHEED MARTIN