The pair are still fighting for their lives after being exposed to Novichok in Salisbury two weeks ago.
ABC News is reporting that intelligence officials said the nature of the substance, described as “dusty”, is now clear.
The US news outlet said UK officials now have a clearer picture of how the attack was carried out and that the Skripals may have been exposed to the substance through his BMW’s ventilation system.
The development comes as counter-terrorism police renewed their appeal for sightings of Mr Skripal’s burgundy BMW 320D saloon car, registration HD09 WAO, in Salisbury on the morning of Sunday March 4.
Metropolitan Police Assistant Commissioner Neil Basu said: “We are learning more about Sergei and Yulia’s movements but we need to be clearer around their exact movements on the morning of the incident.”
Scotland Yard would not comment on the ABC News report.
ABC also reported that intelligence officials said that up to 38 individuals in Salisbury have been identified as having been affected by the nerve agent, but the full impact is still being assessed, and more victims sickened by the agent are expected to be identified.
This is not the first time the US media has reported updates from intelligence officials about incidents in the UK.
British police temporarily suspended intelligence-sharing with the US in the wake of the Manchester Arena bombing last May following a series of leaks to American media.
CBS disclosed the name of the bomber, Salman Abedi, citing US sources, at a time when the British authorities were asking media to withhold the information to protect the investigation.
The New York Times then published detailed photographs taken from the bomb scene which had been taken by British investigators.
Meanwhile, The Sun on Sunday reported that Yulia Skripal’s boyfriend was a Russian secret service agent.
The newspaper also said that Ms Skripal had worked in the US Embassy in Moscow.