The US Air Force deployed the WC-135 Constant Phoenix after a spike in radiation levels across Europe.
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Such planes, designed to detect nuclear explosions, were previously used after the Chernobyl disaster in 1986 and more recently near North Korea.
The Boeing-made jet, using the radio call sign "Cobra 55", flew across the Atlantic to RAF Mildenhall, Suffolk, on Friday.
There has been no statement from the US about the nature of its mission.
Iodine-131 (value +/- uncertainty) in the atmosphere
However air quality stations in Norway, Finland, Poland, Czech Republic, Germany, France and Spain all detected traces of radioactive Iodine-131 in January.
The isotope has a half-life of only eight days, suggesting the particles entered the atmosphere recently. It led some to suggest Vladimir Putin is testing nuclear weapons in Novaya Zemla, a group of remote islands in the Arctic Ocean.
The plane's arrival comes amid growing tension between Russia and the West. Top US officer General Joe Dunford has compared the political climate to that during the Cold War.
Only last week it was revealed Russian jets gave a show of military force by buzzing a US destroyer docked off the Romanian coast. Earlier this month, the US Navy released a statement saying its own testing of two Trident missiles was "not in response to any world events".