Peskov highlighted on Thursday what he called the "unpredictability of Russia's partners across the Atlantic.you can expect anything from Washington", he told CBS News partner network BBC News, calling the USA, "an unpredictable global player".
The second, which can be selectively activated after 90 days if Moscow fails to provide "reliable assurances" it will no longer use chemical weapons and blocks on-site inspections, could include downgrading diplomatic relations, suspending national flag carrier Aeroflot's ability to fly to the United States and cutting off almost all exports and imports. Washington subsequently accused Moscow of breaking the 1991 worldwide law against chemical and biological warfare.
Lawmakers from Russia's ruling party accused USA politicians of treating the country like a punching bag in their partisan infighting and in midterm campaigning.
In June, two more people were taken to hospital after being exposed to the nerve agent.
The sanctions enacted so far this year, and the threat of more, have already inflicted pain on Russia's middle class.
"Our country had been living under constant pressure through sanctions for the last hundred years", Medvedev said, accusing the U.S. and its allies of employing sanctions to undercut global competition.
Weren't Trump and Putin pally recently?
In April 2018, the Trump administration imposed sanctions on seven of Russia's richest oligarchs as well as 17 top government officials, to put pressure on President Vladimir Putin's inner circle. The U.S. said at the time it was the largest expulsion of Russian spies in American history.
Konstantin Kosachev, the chairman of the foreign affairs committee in the upper house of the Russian parliament, said Thursday that the US has behaved like a "police state, threatening and torturing a suspect to get evidence". An administration official said the list of affected items is "enormously elaborate", but exports to Russian Federation that could have a military goal were already banned under the Obama administration.
"We have grown accustomed to not hearing any facts or evidence".
In a statement issued by its embassy in Washington, Russia called charges that Moscow employed chemical weapons "far fetched" - arguing the US lacked evidence, and repeating demands for a new investigation into the poisoning.
"The UK welcomes this further action by our United States allies", a No 10 spokesman said.
Despite assurances, the ruble fell to a two-year low, and shares of Russian companies likely affected by the sanctions - including several banks and Russia's national air carrier Aeroflot - dipped in value.
The Finance Ministry said on Thursday there was no threat to financial stability, a statement markets interpreted as a signal Moscow had no immediate plans to channel any of its $458 billion worth of reserves into propping up the rouble.