The United States has withdrawn its nuclear weapons from Britain after more than 50 years.
The Federation of American Scientists, which studies the US nuclear weapons arsenal, said Washington has removed its nuclear bombs from the Royal Air Force base at Lakenheath, Suffolk where they had been stationed since 1954.
The withdrawal has not been announced officially, but was confirmed by several sources, the report's author, nuclear weapons expert Hans Kristensen, wrote.
The British Ministry of Defence declined to comment.
If true, the withdrawal means US nuclear bombs in Europe are now kept at just six bases, in Belgium, Germany, Holland, Italy and Turkey, with most at Incirlik air base in Turkey and Aviano in Italy, Mr Kristensen wrote.
Bombs dropped from planes stationed at air bases now play a much smaller role in the US nuclear arsenal than they once did, having mostly been replaced by warheads attached to missiles.
But the presence of US nuclear weapons has made the US base at Lakenheath a target for British anti-nuclear protesters for decades.
At the height of the Cold War, the United States had more than 7,000 nuclear weapons in Europe. Most were withdrawn in the early 1990s, and today, Mr Kristensen estimates the number at fewer than 240.
But he said it was "a puzzle" that Washington and NATO have not publicly announced the withdrawal of weapons from Britain at a time when they are arguing with Russia over weapons cuts.
"By keeping the withdrawals secret, NATO and the United States have missed huge opportunities to engage Russia directly and positively about reductions to their non-strategic nuclear weapons, and to improve their own nuclear image in the world in general," he wrote.