Russian lawmakers on Tuesday mounted a fierce defense of U.S. President Donald Trump's national security adviser, who has resigned following reports that he misled White House officials about his contacts with Russia.

Michael Flynn handed in his resignation late Monday night, conceding that he gave "incomplete information" about his calls with Russia's ambassador to the U.S.

A U.S. official told The Associated Press that Flynn was in frequent contact with Ambassador Sergey Kislyak on the day the Obama administration slapped sanctions on Russia for election-related hacking, as well as at other times during the transition. The Kremlin has confirmed that Flynn has been in contact with Kislyak but denied that they talked about lifting sanctions.

Konstantin Kosachev, chairman of the foreign affairs committee at the upper chamber of the Russian parliament, said in a post on Facebook that firing a national security adviser for his contacts with Russia is "not just paranoia but something even worse."

Kosachev also expressed frustration at the Trump administration:

"Either Trump hasn't found the necessary independence and he's been driven into a corner... or russophobia has permeated the new administration from top to bottom."

Kosachev's counterpart at the lower chamber of the Russian parliament, Alexei Pushkov, tweeted shortly after the announcement that "it was not Flynn who was targeted but relations with Russia."