Novichok agents: All about the chemical weapon used in ex-Russian spy's poisoning What are Novichoks?

Speaking today, the United Kingdom's Prime Minister Theresa May identified the poison used in an attack on a former Russian spy and his daughter as a type of “military grade” nerve agent developed by Russia known as "Novichok."

Novichok — which means "newcomer" in Russian — is the codename for a series of nerve agents that Russia allegedly secretly developed in the latter stages of the Cold War. Novichok nerve agents were intended to be more powerful and harder to detect than previous generations of nerve agents.

Russia has never officially acknowledged the existence of the Novichok program and most of what is publicly known about it comes from Vil Mirzayanov, a Russian scientist who worked for years in the Soviet chemical weapons program.

Mirzayanov had been tasked with ensuring the secrecy of Russia’s chemical weapons program but came to believe the country was violating the Chemical Weapons Convention that it had recently signed onto with the United States. So in 1992, he and another scientist, Lev Fedorov, went public, writing an article first in the newspaper Moscow News and then giving interviews to Western journalists about the program.

According to the scientists, the Soviets had successfully developed a new type of so-called binary nerve agent. Earlier generations of chemical weapons, including versions of more common nerve gases such as sarin, VX and soman, are usually unitary, meaning the component chemicals are mixed during manufacture and so the nerve agent is immediately dangerous; a binary weapon, meanwhile, consists of two substances that must be combined in order to trigger their lethal effects, making them easier to transport.

In an academic article published in 1995 by the Stimson Center, Mirzayanov said he believed the first Novichok — known as Novichok No. 5 — was five to eight times more effective than VX gas, the lethal nerve agent that was used to assassinate the North Korean dictator Kim Jong Un’s half-brother, Kim Jong-Nam, last year.

Vladimir Uglev, another Soviet scientist, in 1998 told The Washington Post that one of the advantages of a Novichok precursor nerve agent, called A232, was that it could be frozen. Mirzayanov wrote the Novichok agents could also be created using more basic agricultural fertilizer materials, which he said was intended to make it easier to conceal their purpose from weapons inspectors.

Chemical weapons experts said the Novichok poisons work like other nerve agents: They attack a victim’s nervous system, causing them to lose control of bodily functions, prompting cardiac arrest and shutting down the respiratory system.

Novichok agents, however, are unusual for their strength, Gwynn Winfield, a chemical weapons expert with the publication CBRNe World, told ABC News. He said they required much larger doses of more complicated antidotes.

“Once you start talking about Novichok, you need far, far more,” Winfield said.

Winfield said that the Russian double agent Sergei Skripal and his daughter Yulia appeared to have been exposed to the nerve agent via their skin, since they left a trail around Salisbury, England, where they were found. Skripal could have picked it up from a contaminated object, but “equally there could have been an individual that just stood behind him while he was walking and just sprayed the back of his clothes and as it absorbed through the clothes it got on his skin,” Winfield said.

Winfield said he believes that the fact that Skripal and his daughter Yulia are still alive -- though in critical condition -- shows the assassins “messed up.”

“He should've been dead in five to 10 minutes,” he said. Other experts have said the window in which it took the Skripals to collapse was consistent with the effects of nerve agents.

May in her statement said the use of a Novichok-type agent meant either the Russian state had ordered the attack or else it had lost control of one of its chemical weapons. She said Russia has until midnight Wednesday to provide a “credible” response explaining that or otherwise the U.K. will retaliate. That retaliation is likely to include diplomatic expulsions, fresh sanctions and possibly increased troop deployments in eastern Europe.

Russia’s response so far has given no indication it will acquiesce. Maria Zakharova, a spokeswoman for Russia’s foreign ministry, called May’s allegations a “fairy tale” in comments to the news agency Interfax.

Britain’s foreign minister Boris Johnson has demanded that Russia provide “full and complete disclosure” of the Novichok program to the Organisation for the Prohibition of Chemical Weapons (OPCW).

While Russian authorities never acknowledged the Novichok agents, they inadvertently confirmed their existence when they charged Miryazanov with leaking state secrets in 1993. Under international pressure, the KGB dropped the case against Miryazanov, who eventually moved to the United States.

Mirzayanov wrote in the 1990s he believed Russia had created only "experimental quantities" of the Novichok agents, but that would still mean tens of tons. The Washington Post in 1998 quoted him that much of them had been blown up by Russia’s military to conceal their existence but he was unsure they had been entirely destroyed.

Cindy Vestergaard, a chemical weapons expert at the Stimson Center, said that nerve agents have recognizable signatures that can be matched to those usually used by different countries.

Winfield said he believed the use of Novichok agents on the Skripals was meant to send a message about Russia’s chemical weapons capabilities under President Vladimir Putin, who recently boasted of an array of elaborate additions to the country's nuclear arsenal as well.

“I think that's one of the reasons why it was chosen,” Winfield said. “It's a very clear signal not only to but also to the British government that there are exotic weapons out there that are far more terrifying than the ones we currently consider today.”