Agents seized files relating to Cohen's work, which included making a $130,000 payment before the 2016 election to an adult film actress who says she had a tryst with the Trump.
US officials confirmed that their action against the oligarchs was in part related to Russia's interference in US politics, but stressed the broader nature of their concerns.
George Nader, an adviser to the UAE who is now a witness in the US special counsel investigation into foreign meddling in American politics, wired USD 2.5 million to the Trump fundraiser.
Dowd quit days after Trump directly attacked Mueller's investigation as a "witch hunt," raising questions about whether the president was interfering with the probe.
Trump's legal team recently shared the documents in an effort to limit any session between the President and Mueller to a few select topics, informed sources told The Washington Post on Monday night.
With the surprise indictment Friday of 13 Russians for meddling in the US election, Special Counsel Robert Mueller's investigation has entered new territory.
Robert Mueller alleges that by mid-2016, the campaign -- under the direction of Yevgeny Prigozhin, a close ally of Russian President Vladimir Putin -- became focused on boosting Trump.
The memo also includes revelations that might complicate efforts by Trump and his allies to undermine special counsel Robert Mueller's inquiry.
A year into his presidency, Trump stands before the nation Tuesday night to account for his promise to "make America great again" amid nuclear war talks and Mueller's Russia probe.
US Republicans vote to release secret memo alleging missteps by FBI, Justice Department in Russia probe
Republicans have said the memo reveals grave concerns about abuses of the government surveillance powers in the Russia investigation.
President Donald Trump pushed back against reports that he ordered White House lawyer Don McGahn to fire special counsel Robert Mueller last June.
Mueller is leading the probe into allegations of collusion between the US president's campaign team and Russia in the 2016 election.
Trump gave the order in June 2017, according to the Times, but White House counsel Don McGahn refused, saying it would have a "catastrophic effect" on Trump's presidency.
He is referring to the special counsel's probe of Russian election interference and Trump's possible obstruction in the firing of the FBI director.
A day earlier, the US Justice Department had confirmed that Attorney General Jeff Sessions was questioned by Mueller on his investigation.