Around 180 soldiers have been deployed to Salisbury following a nerve agent attack on a Russian ex-spy and his daughter. British police said the "public should not be alarmed" to see the military on the streets.
"The public should not be alarmed," said counterterrorism police in a statement. "Military assistance will continue as necessary during this investigation."
Defense Secretary Gavin Williamson said the British armed forces "have the right people with the right skills" to tackle the crime scene. Around 180 soldiers are to be deployed, including Royal Marines and chemical specialists.
Sergei Skripal was jailed in Russia for betraying fellow spies and was later released in a prisoner swap with the UK and US
Several casualties
Sergei Skripal, a 66-year-old former military intelligence agent who betrayed several Russian agents to British intelligence, and his 33-year-old daughter Yulia remain unconscious in intensive care following the attack.
Nick Bailey, the first police officer on the scene, is also in stable but critical condition. Up to 21 other people were treated for exposure, said Wiltshire Police chief constable Kier Pritchard.
British Home Secretary Amber Rudd said authorities needed to conduct more tests to determine who the culprits are, saying further action "will have to wait until we're absolutely clear what the consequences could be, and what the actual source of this nerve agent has been."
Poisoning has been used by intelligence agencies for over a century and the latest alleged victim is Putin critic Alexei Navalny. Toxins and even nerve agents, hidden in food or drink, are often the weapons of choice.
Image: Imago Images/Itar-Tass/S. Fadeichev
Alexei Navalny
Russian opposition leader Alexei Navalny was rushed to hospital in Siberia after being taken ill on a flight to Moscow. His aides allege he was poisoned in revenge for his campaigns against corruption. The 44-year-old ex-lawyer apparently only drank black tea before taking off from Omsk airport, which his team think was laced with a toxin that put him in a coma.
Image: Getty Images/AFP/K. Kudrayavtsev
Pyotr Verzilov
In 2018, Russian-Canadian activist Pyotr Verzilov was reported to be in a critical condition after allegedly being poisoned in Moscow. It happened shortly after he gave a TV interview criticizing Russia's legal system. Verzilov, the unofficial spokesman for the rock group Pussy Riot, was transferred to a hospital in Berlin where doctors said it was "highly probable" that he had been poisoned.
Image: picture-alliance/dpa/Tass/A. Novoderezhkin
Sergei Skripal
Sergei Skripal, a 66-year-old former Russian spy, was found unconscious on a bench outside a shopping center in the British city of Salisbury after he was exposed to what was later revealed to be the nerve agent Novichok. Russian President Vladimir Putin’s spokesman Dmitry Peskov called the situation "tragic" but said, "We don't have information about what could be the cause" of the incident.
Image: picture-alliance/dpa/Tass
Kim Jong Nam
The estranged half-brother of Kim Jong Un was killed on February 13, 2018 at Kuala Lumpur airport after two women allegedly smeared the chemical nerve agent VX on his face. In February, a Malaysian court heard that Kim Jong Nam had been carrying a dozen vials of antidote for the deadly nerve agent VX in his backpack at the time of the poisoning.
Image: picture-alliance/AP Photo/S. Kambayashi
Alexander Litvinenko
Former Russian spy Litvinenko had worked for the Federal Security Service (FSB) before he defected to Britain, where he became a journalist and wrote two books of accusations against the FSB and Putin. He became ill after meeting with two former KGB officers and died on November 23, 2006. A government inquiry found he was killed by radioactive polonium-210 which it alleged the men put in his tea.
Image: picture-alliance/dpa/S. Kaptilkin
Viktor Kalashnikov
In November 2010, doctors at Berlin's Charité hospital discovered high levels of mercury had been found in a Russian dissident couple working in Berlin. Kalashnikov, a freelance journalist and former KGB colonel, had 3.7 micrograms of mercury per litre of blood, while his wife had 56 micrograms. A safe level is 1-3 micrograms. Viktor reportedly told German magazine Focus that "Moscow poisoned us."
Image: picture-alliance/dpa/RIA Novosti
Viktor Yushchenko
Ukrainian opposition leader Yushchenko became sick in September 2004 and was diagnosed with acute pancreatis caused by a viral infection and chemical substances. The illness resulted in facial disfigurement, with pockmarks, bloating and jaundice. Doctors said the changes to his face were from chloracne, which is a result of dioxin poisoning. Yushchenko claimed government agents poisoned him.
Image: Getty Images/AFP/M. Leodolter
Khaled Meshaal
On September 25, 1997, Israel's intelligence agency attempted to assassinate Hamas leader Meshaal, under orders from Prime Minister Benjamin Netanyahu. Two agents sprayed a poisonous substance into Meshaal's ear as he walked into the Hamas offices in Amman, Jordan. The assassination attempt was unsuccessful and not long afterward the two Israeli agents were captured.
Image: Getty Images/AFP/A. Sazonov
Georgi Markov
In 1978, Bulgarian dissident Markov was waiting at a bus stop after a shift at the BBC when he felt a sharp jab in his thigh. He turned to see a man picking up an umbrella. A small bump appeared where he felt the jab and four days later he died. An autopsy found he'd been killed by a small pellet containing a 0.2-milligram dose of ricin. Many believe the poisoned dart was fired from the umbrella.
Image: picture-alliance/dpa/epa/Stringer
Grigori Rasputin
On December 30, 1916, mystic and spiritual healer Rasputin arrived at Yusupov Palace in St Petersburg at the invitation Prince Felix Yusupov. There, Prince Yusupov offered Rasputin cakes laced with potassium cyanide but he just kept eating them. Yusupov then gave him wine in a cyanide-laced wine glasses, but still Rasputin continued to drink. With the poison failing, Rasputin was shot and killed.
