The former aide was the first person to be arrested as part of the special counsel's investigation.
His case was the first to detail a member of the Trump campaign having knowledge of Russian efforts to interfere in the 2016 U.S. presidential election while it was ongoing.
Papadopoulos later used his connections with the Maltese professor, Joseph Mifsud, and other Russian nationals in an attempt to broker a meeting between then-candidate Trump and Russian President Vladimir Putin.
In court Friday, prosecutor Andrew Goldstein said Papadopoulos' cooperation "didn't come close to the standard of substantial assistance".
Alex Van der Zwaan, a lawyer who once worked closely with Manafort and Gates, pleaded guilty in February to lying to Mueller's investigators about contacts with an official in the Trump election campaign. "But they got him, I guess, on a couple of lies, I guess that's what they're saying".
They said prosecutors have not provided any proof that Papadopoulos "actually harmed the investigation as alleged".
He has testified that senior members of the Trump campaign encouraged him during 2016 to build ties with Russian Federation, including after he told them that Moscow possessed - and could be willing to share - dirt on Hillary Clinton, Trump's election rival.
"The President of the United States hindered this investigation more than George Papadopoulos ever did", Breen said.
Out of the 35 people and entities so far charged, Papadopoulos is one of five who have pleaded guilty and the second to be sentenced.
"I wanted to distance myself as much as possible - and Trump himself and the campaign - from what was probably an illegal action or unsafe information", he said.
Defense counsel in their filings painted Papadopoulos as a naive and eager campaign aid who sought to impress the Trump campaign by setting up a meeting with campaign officials and Russian Federation to discuss whatever Russian Federation allegedly had on Ms. Clinton.
According to Papadopoulos's account, "Mr. Trump nodded with approval" when he brought up a possible meeting and "deferred to Mr. Sessions who appeared to like the idea and stated that the campaign should look into it".
The memo went on to say that Papadopoulos was "ashamed and remorseful", but he did not always seem that way on social media.
Papadopoulos was arrested more than a year ago and pleaded guilty to lying to investigators about his contacts with several people connected to Russian Federation during the campaign.
"I made a terrible mistake, but I am a good man who is eager for redemption", Papadopoulos said at his sentencing hearing.
In subsequent campaign communications, Papadopoulos was encouraged to pursue a Putin-Trump meeting. He recalled how he and attorney Robert Stanley and Papadopoulos visited the Federal Bureau of Investigation office in Chicago months ago and noticed the photos of Attorney General Jeff Sessions and Trump hanging on the lobby wall.
"We were hoping for no jail time but two weeks is OK", Maria Stamatopoulos said.