The Trump administration is imposing a host of new sanctions against Russia over the poisoning of a former British spy, after months of discussion about how to respond to the March attack on Sergei and Yulia Skripal.
Although the US joined European countries in publicly blaming Moscow within days of the attack, the Trump administration had never issued the formal determination that triggers automatic sanctions under a decades-old US law on chemical weapons.
Their declaration that Russia violated international law brings into effect sanctions limiting exports to Russia and financing of the deals with the country.
The biggest impact from the initial sanctions is expected to come from a ban on granting licenses to export sensitive national security goods to Russia, which in the past have included items like electronic devices and components, along with test and calibration equipment for avionics. Prior to the sanctions, such exports were allowed on a case-by-case basis.
Commercial aviation and space technology will largely be exempt, the state department said.
Mr Putin has strongly denied Russia was behind the nerve agent attack
But the new prohibitions, which come into effect on August 22, could cut off hundreds of millions of dollars in future exports to Russia.
In addition, a second, more painful round kicks in three months later unless Russia provides "reliable assurances" that it won’t use chemical weapons in the future and agrees to "on-site inspections" by the UN — conditions unlikely to be met.
The second round of sanctions could include downgrading diplomatic relations, suspending state airline Aeroflot’s ability to fly to the US, and cutting off nearly all exports and imports.
Mike Pompeo, the secretary of state, said Russia had violated international law by using a chemical weapon.
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Vladimir Putin, the Russian president, accused Britain of making baseless accusations over the poisonings and suggested the case could be driven by domestic issues in the UK.
Wednesday’s announcement comes months after Congress made a formal request for Mr Trump to determine that Russia had violated international law.
Officials pushed back on the delay on Wednesday, saying the administration always took time to examine the evidence before coming to a concrete decision.
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The sanctions came as an eagerly-watched contest for a previously safe Republican seat in the US congress went down to the wire, leading to speculation that voters are turning against Donald Trump and could punish the Republican Party at the mid-term elections.