Russian Federation has refused Britain's demands to explain how Novichok, a nerve agent developed by the Soviet military, was used against the Skripals in the English city of Salisbury.
"If the latter, a connection to Russian mafia-like groups that have been allowed to gain a toehold in Britain can not be excluded", he said.
She landed at Heathrow at 2.40pm on March 3, and she and her father were found collapsed at 4.15pm the following day.
Trump, who has often been reluctant to criticize Russian President Vladimir Putin, said it "certainly looks like the Russians were behind it".
She announced a range of economic and diplomatic measures, including the suspension of high-level contacts with Russian Federation.
The U.K. has said a military-grade nerve agent was used in the attack, of a type known as a "Novichok", which is a chemical weapon secretly developed by Russian Federation at the end of the Cold War.
Russian Foreign Minister Sergey Lavrov said, "The response will come very quickly, I can assure you", Tass reports.
Asked by a Reuters journalist if Russian Federation intends to respond to the deportations announced by the British, the head of British diplomacy said: "We will do it, of course".
Deputy UK Ambassador to the UN Jonathan Allen, who spoke ahead of Haley at Wednesday's meeting, called the attack "an unlawful use of force" and invited representatives from the Organization for the Prohibition of Chemical Weapons to conduct an independent investigation of the incident.
"The Met Police's Counter Terrorism Command, which has led the investigation from the outset, is now treating Mr. Glushkov's death as murder", the statement said.
The Russian president said in a televised address that "the will of the people, the will of each Russian citizen, will determine the path the country will take".
She has given Moscow until midnight on Tuesday to come up with a meaningful response to the evidence gathered by British investigators.
On Thursday, British Defense Secretary Gavin Williamson said Moscow had made a "deliberate political decision" to poison Skripal. It is now a scene of police tape and forensic tents, one of several scattered across the quiet cathedral city as police, supported by troops with chemical-weapons training, try to discover how and where the poison was administered.
Detective Sergeant Nick Bailey, who was also part of the initial response to the incident, is conscious and in a stable condition, NHS England has said.
President Vladimir Putin, a former KGB spy who is poised to win a fourth term in an election on Sunday, has so far only said publicly that Britain should get to the bottom of what has happened.
In a sign of just how tense the relationship has become, British and Russian ministers used openly insulting language while the Russian ambassador said Britain was trying to divert attention from the difficulties it was having managing its exit from the European Union.
British Foreign Secretary Boris Johnson had told reporters that it was "overwhelmingly likely" that Putin ordered the attack.
As the tit-for-tat exchange between Russian Federation and the United Kingdom has intensified, May and Foreign Secretary Boris Johnson have been working to align their allies with the U.K.'s stance, talking with France's President Emmanuel Macron, German Chancellor Angela Merkel and President Trump.