WASHINGTON – Justice Department special counsel Robert Mueller has requested a November sentencing date for former National Security Adviser Michael Flynn, signaling that the former Army general has completed his cooperation with federal investigators in the ongoing inquiry into Russia's interference in the 2016 election.

In a joint filing Monday, prosecutors and Flynn's attorney, Robert Kelner, suggested a Nov. 28 date. The filing comes just days after former Trump campaign chairman Paul Manafort struck his own cooperation agreement with Mueller while pleading guilty to obstructing justice and a conspiracy to defraud the government.

Flynn pleaded guilty in December to lying to the FBI about his conversations with Russian Ambassador Sergey Kislyak before President Donald Trump's inauguration. He faces a maximum penalty of five years in prison, but his cooperation with prosecutors is expected to weigh heavily in a request for a reduced sentence.

Prosecutors charged that Flynn falsely told FBI agents he did not ask Kislyak to delay a vote on a pending United Nations Security Council resolution critical of Israeli settlements.

Prosecutors also charged that Flynn lied to agents about a Dec. 29 conversation about how Russia might respond to sanctions the U.S. government had levied over its election meddling. President Barack Obama imposed those sanctions Dec. 28; the same day, Kislyak contacted Flynn to discuss how the Russian government would respond.

Russian President Vladimir Putin said the next day that his government would not retaliate for the sanctions. Trump praised Putin's move on Twitter, writing, "I always knew he was very smart!"

While incoming presidents traditionally have calls with world leaders during the transition, it is unusual for aides to begin conducting foreign policy of any kind before the inauguration.

Flynn's contacts with Kislyak, which were discovered by federal investigators who regularly monitor the communications of foreign diplomats in the U.S., prompted then-Acting Attorney General Sally Yates to alert White House Counsel Don McGahn.

Yates, who was abruptly fired by Trump for refusing to defend the president's disputed travel ban, later told a Senate panel that she feared Flynn's communications could have made him vulnerable to Russian blackmail.