A ‘nuclear sniffer’ plane has been sent to monitor radioactivity levels in Europe following the detection of mysterious spikes of radiation across the continent.
The US military plane, called the WC-135 Constant Phoenix, landed at an air base in Surrey, a spokesperson at RAF Mildenhall confirmed to The Independent.
It is now on its way towards Norway and the Barents Sea north of Russia in the arctic circle, according to The Aviationist.
The WC-135 can detect and identify nuclear explosions from the air and is also used to track radioactivity after nuclear incidents such as the 1986 Chernobyl disaster.
A US air force spokesperson said the aircraft is in Europe "on a preplanned rotational deployment scheduled far in advance," adding: "anything contrary is completely baseless."
"The WC-135 routinely conducts worldwide missions and we are not going to get into further details," they said.
Man-made radioactive material Iodine-131 was found in Norway in early January and has since been detected in small amounts across Europe, officials have said.
It isn't clear where Iodine-131 would ever have been released from, but conspiracy theorists have pointed to the fact that the spread appeared to emanate from northern Norway, where Russia may have run a secret nuclear test.
The tragic recent history of Russian aviation
The tragic recent history of Russian aviation
1/10 3 July 2001
A Russian TU-154 'Dalavia' aircraft with 143 people on board dropped out of contact and crashed in southern Siberia
ALEXANDER NEMENOV/AFP/Getty Images
2/10 1 July 2002
Victims' relatives gather at the wreckage of the crashed Russian Tupolev 154 passenger plane near Ueberlingen, Germany. The Bashkirian Airlines plane was involved in a mid-air collision with a cargo jet over German soil, killing 71 people.
PIERRE ANDRIEU/AFP/Getty Images
3/10 25 August 2004
A Russian policeman checks the luggage and ID papers of passengers at Moscow's Domodedovo airport after the crashes of two jetliners minutes apart raised fresh questions about aviation security in Russia. Russian intelligence experts closely examined the possibility that two passenger planes, that crashed almost simultaneously, were brought down by terrorists, an FSB spokesman said.
4/10 10 July 2006
Relatives of Airbus A-310 crash victims, cry at Irkutsk airport, after 137 people were killed when the passenger plane veered off a runway, slammed into a concrete wall and burst into flames while landing in the Siberian city of Irkutsk.
ALEXANDER NOVIKOV/AFP/Getty Images
5/10 14 September 2008
Investigators look at the remains of Aeroflot-Nord Boeing 737 after a crash in Perm. All 88 people on board died including 21 foreign nationals, from countries including France, Germany and the United States
KIRILL KUDRYAVSTSEV/AFP/Getty Images
6/10 5 December 2010
Police investigate the wreckage of Dagestan Airlines Flight 372, which rolled off the runway at Domodedovo airport and broke up into three pieces, killing two and injuring more than 80 of the 169 people on board.
ANDREY SMIRNOV/AFP/Getty Images
7/10 24 January 2011
People lay flowers in central Moscow on January 2011 as they pay tribute to 35 people killed in a suspected suicide bombing in Moscow's Domodedovo airport. Russian opposition denounced the policies of Vladimir Putin's government and inefficiency of security forces following the blast.
Alexey SAZONOV/AFP/Getty Images
8/10 29 December 2012
Four crew were killed when a Red Wings Tu-204 jet crashed into a motorway and broke up into three pieces after overshooting the runway at Vnukovo airport outside Moscow.
NATALIA KOLESNIKOVA/AFP/Getty Images
9/10 17 November 2013
Relatives read lists of passengers killed when a Boeing 737 operated by Tatarstan Airlines crashed while attempting to land at the airport of the Volga city of Kazan, killing all 50 on board.
ROMAN KRUCHININ/AFP/Getty Images
10/10 31 October 2015
The Russian airline Kogalymavia’s Airbus A321 on an airstrip of Moscow’s Domodedovo international airport. The Russian passenger plane crashed in Sinai, Egypt with more than 200 people. The Airbus A-321, which belongs to the airline Kogalymavia was due to land in St Petersburg.
AP Photo/Tatiana Belyakova
Iodine-131 is perhaps most closely associated with atomic bombs, and was found throughout the world after those were tested. It is usually found alongside other radioactive materials, but in this case it wasn't.
And it has a short half-life – the time required for one half of the atoms of a radioactive substance to disintegrate – but a significant amount of it was found, meaning that it is likely that it was introduced very recently.
The material is also being used to treat some cancers and other illnesses. The fact that the material was found on its own likely suggests that it had been isolated, and so makes it more likely that the leak came from a pharmaceutical company that hasn't reported it to authorities.
The WC-135, sometimes known as the “sniffer”, can carry up to 33 personnel, but often carries fewer in an attempt to lessen the risk of exposure to radioactive materials.
Two devices on either side of the aircraft collect atmospheric gases, filtering them to detect particles from nuclear fallout.
There is no imminent threat from the amount of material that is currently being found in Europe, according to the French IRSN, or nuclear security body.
The IRSN said that it had shared the findings with the “Ring of Five” – a group of similar bodies across Europe – so that they can be further investigated.