Donald Trump's sudden decision to fire the FBI director James Comey over the Russian interference in the US elections keeps Washington in shock.

On Wednesday, General Michael Flynn, the dismissed National Security Adviser, was summoned by the Senate Intelligence Committee to hand over all documents linking him to Russia. Among them is a list of his possible possessions and assets in that country, as well as the records, recordings and annotations of his meetings with Russian officials between June 16, 2015, the date of the start of Donald Trump's campaign, until his investiture, on January 20th.

The mandatory request by the powerful Senate Commitee  comes after Flynn voluntarily refused to deliver the information.

"Everything has been voluntary up to this point, and we've interviewed a lot of people and I want to continue to do it in a voluntary fashion. But if in fact the production of things that we need are not provided, then we have a host of tools,"  committee chairman Republican Richard Burr told the Washington Post newspaper.

Flynn has come under scrutiny since Trump assumed the presidency in January. He was forced to resign after lying about his contact with the Russian ambassador to the US in Washington.   Flynn and Ambassador Sergey Kislyak held talks in Washington DC before the Nov. 8 presidential elections as well as during the transition period between President Barack Obama's government and the Trump administration.

Along with Flynn, other former Trump election advisors have been named. The investigation, which runs parallel to the one being conducted by the FBI and another House committee, seeks to determine whether the president's campaign team coordinated with the Kremlin in its attacks on Democrat Hillary Clinton campaign.

Also on Wednesday, former FBI director James Comey released a public letter in which he urged the agency he led until his sudden dismissal by Trump to remain “a rock of competence, honesty, and independence”.

In the letter, first obtained by the CNN, Comey stated that Trump, as president, had a right to fire him irrespective of the circumstances.

“I have long believed that a president can fire an FBI director for any reason, or for no reason at all,” Comey wrote in the letter.

“It is done, and I will be fine, although I will miss you and the mission deeply.”

Requests for an independent investigation on the Russian interference have not only come from Comey, but from other Democrat senators and lawmakers. 

The NY Times run an open letter addressed to Deputy Attorney General Rod Rosenstein to intervene in order to safeguard American democracy. 

"Even before President Trump’s shocking decision on Tuesday to fire the F.B.I. director, James Comey, a dark cloud of suspicion surrounded this president, and the very integrity of the electoral process that put him in office. At this fraught moment you find yourself, improbably, to be the person with the most authority to dispel that cloud and restore Americans’ confidence in their government. We sympathize; that’s a lot of pressure," the letter reads.

Democrat Senator Bob Casey from Pennsylvania also posted a statement on Facebook requesting Deputy D.A Rosenstein intervention on the Russian intervention, to make sure is carried on with independence. 

“This is Nixonian. Deputy Attorney General Rod Rosenstein must immediately appoint a special counsel to continue the Trump/Russia investigation,” Casey posted. And then he added:

 On March 20th Director Comey said, “I have been authorized by the Department of Justice to confirm that the FBI, as part of our counterintelligence mission, is investigating the Russian government's efforts to interfere in the 2016 presidential election and that includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia's efforts.” This investigation must be independent and thorough in order to uphold our nation’s system of justice.