The US expelled a number of Russian diplomats as part of an global response to the attack, when the former double agent Sergei Skripal and his daughter were taken ill in March.
When asked Thursday about the possibility of a ban on Aeroflot, Peskov labelled the United States administration an "unpredictable participant in worldwide affairs", adding "you can now expect anything". The currency sank toward its weakest close since November 2016.
She said sanctions would take effect on or around 22 August, after a 15-day Congressional notification period. Instead, he said there were also delays in triggering the same type of US sanctions after the two most recent chemical or biological attacks, one in Sryia by the Assad regime and another perpetrated by North Korea. Moscow, in turn, responded to the worldwide action by ordering its own expulsion of foreign diplomats.
This is hard to envision, since Moscow has denied responsibility for the attack from the start. A ban on Aeroflot flights to the United States could lead to a ban on US airlines traversing Russian airspace.
The state department says "more draconian" sanctions will follow within 90 days if Russian Federation fails to give reliable assurances that it will no longer use chemical weapons and will allow on-site inspections by the United Nations.
But the punitive measures triggered a furious reaction from Moscow.
The sanctions enacted so far this year, and the threat of more, have already inflicted pain on Russia's middle class.
Finance minister Anton Siluanov assured Russians that the government and the central bank have "all the necessary tools to ensure financial stability", saying the economy has become more resistant to external shocks in recent years.
The Kremlin acknowledged on Thursday Putin's office had received the letter, but Peskov suggested the Russian leader was yet to parse it.
The US and European Union (including the UK) also enforced sanctions against Russia in 2014 as a result of the Russia-Ukraine conflict. This included siding with the Russian leader over US intelligence regarding alleged Kremlin interference in the 2016 elections that brought Trump to the White House. In fact, a new spike in tensions with Washington could provide a convenient distraction for the Kremlin at a time when Putin faces domestic discontent over the government's effort to raise the retirement age.
Weren't Trump and Putin pally recently?
But "smart sanctions" are sometimes used - they're much more targeted and created to only punish a small number of people rather than an entire nation.
Proposed US legislation prepared by several senators calls on Trump to widen the sanctions to include virtually all Russian energy projects and effectively bar Western companies from any involvement in the country.