A French diplomatic official said Tuesday that Britain had informed France about the details of its investigation.
At the same time, the lab's job is "to provide the scientific evidence that identifies what the particular nerve agent is. but it's not our job to say where that was actually manufactured", he said.
Sergei Skripal - who settled in Britain after a 2010 spy swap - remains critically ill in hospital.
Trump reiterated his long-standing call for better relations with Moscow, despite a series of conflagrations and crises, including Russian meddling in the United States election and the poisoning of a Russian double agent on British soil.
Russian officials and state television have in turn come up with several different theories to explain the poisoning.
The State Department confirmed the United States and Russian Federation can replace diplomats in each other's countries who were expelled last week, describing the process as standard practice for cases in which targeted personnel are ejected as "persona non-grata", and cautioning that any new diplomats would be subject to approval on a "case-by-case basis".
Russian Federation denies responsibility and has suggested the poison may have come from Britain.
He argued that experts have said that such nerve agents could have been made in some 20 countries.
However, he said that Novichok required the sophistication "only in the capabilities of a state actor".
The location of manufacture "can be established through a number of different input sources which the Government has access to", he said, adding: "From our perspective, scientific evidence is only one of those sources, and it requires a number of other things to verify that".
The global chemical weapons control body will hold an emergency meeting to discuss the poisoning of former spy Sergei Skripal, at Russia's request. "These realities naturally prompt us to conclude that this is a provocation made by the special services", the diplomat stressed.
Evgeny Buzhinskiy has warned the expelling of diplomats over the attack on Sergei Skripal and his daughter Yulia is creating a situation which is "worse than the Cold War".
"This could be in the interests of the British government which found itself in an uncomfortable situation having failed to fulfil promises to its electorate about the conditions for Brexit", Lavrov said at a press conference in Moscow, referring to Britain's planned departure from the European Union.
On Saturday, Russian Foreign Ministry spokeswoman, Maria Zakharova, wrote on Facebook that more than 50 diplomats and staff members of the United Kingdom diplomatic mission in Russia would have to return to the United Kingdom in order to maintain the parity in the number of diplomatic personnel of the two countries.
Manufacturers are anxious about Trump tariffs
In March, the White House took aim at unfair practices concerning IT services in China under section 301 of the USA trade act. Observers have suggested that Beijing may be saving stronger retaliatory measures for a response to that White House plan.
Kawhi Leonard Has Returned To New York For Rehab
The Kawhi Leonard-San Antonio Spurs saga has continued to unfold as the regular season slowly comes down to an end. Wojnarowski reported that Leonard planned to play in San Antonio's game on March 15, but that plan was aborted.
Jayhawks hope Graham can lead them past Final Four
KU-Villanova is regarded as a real title game of sorts before the victor plays Loyola or MI on Monday in San Antonio . They've beaten two ACC teams in Clemson and Duke, and now they'll face the toughest challenge to date in Villanova .