President Donald Trump gestures as he speaks to Navy and shipyard personnel aboard nuclear aircraft carrier Gerald R. Ford at Newport News Shipbuilding in Newport News, Va., Thursday, March 2, 2017. The ship which is still under construction is due to be delivered to the Navy later this year. AP Photo / Steve Helber

President Donald Trump pardoned a Navy sailor who took photographs of classified areas of a military submarine.

The sailor, Kristian Saucier, served 12 months in prison after pleading guilty to one count of unauthorized possession and retention of national defense information.

It's Trump's second pardon, after he pardoned the former Arizona sheriff Joe Arpaio, who was convicted of criminal contempt.

President Donald Trump has pardoned a Navy sailor who took photographs of the classified areas of a military submarine.

Kristian Saucier pleaded guilty in 2016 to taking the photos inside the USS Alexandria in 2009. He served a 12-month prison sentence for the crime.

Trump referenced Saucier's case often on the campaign trail as he criticized his Democratic rival Hillary Clinton's use of a private email server while she was secretary of state.

Saucier has said he merely wanted service mementos. But federal prosecutors said he was a disgruntled sailor who compromised national security and then obstructed the investigation by destroying a laptop and camera.

The news was announced by White House Press Secretary Sarah Huckabee at a briefing Friday. It is only Trump's second pardon, after the president pardoned Joe Arpaio, an ardent Trump supporter and former Phoenix sheriff who was convicted of criminal contempt, in August 2017.

The investigation began in March 2012, when Saucier's cellphone, with pictures of the submarine still on it, was found at a waste-transfer station in Connecticut. Saucier was charged with taking photos of classified spaces, instruments, and equipment in July 2015 and pleaded guilty to one count of unauthorized possession and retention of national defense information in May 2016.

In addition to a year in jail, he was given an "other than honorable" discharge from the Navy.

Then Republican presidential nominee Donald Trump at a campaign rally in Pensacola, Florida, September 9, 2016. REUTERS/Mike Segar

Trump referenced Saucier's case numerous times during his campaign - in one speech, Trump referred to Saucier - a 22-year-old sailor at the time the photos were taken - as "the kid who wanted some pictures of the submarine."

Vice President Mike Pence also said during an October 2016 debate that a service member who handled classified information the way Clinton did would "absolutely" face court-martial, though The Washington Post found it was far from clear that would happen. Saucier's lawyer also compared the six photos his client took to the 110 classified emails the FBI found were on the private email server Clinton used while she was secretary of state.

The judge in the case appeared to dismiss the comparison, as well as the argument that Saucier was being treated differently, saying "selective enforcement is really not a good argument" that didn't "really carry much water."

Saucier was released to house arrest at the end of summer 2017 and said later that year he thought "punishment isn't doled out evenly" and that he hoped Trump would "make right by it."

On Saturday morning, hours after Huckabee said the president was "appreciative" of Saucier's service to the country, Trump tweeted his congratulations to the former sailor, calling him "a man who has served proudly in the Navy."

"Now you can go out and have the life you deserve!" Trump said.

NOW WATCH: Popular Videos from Insider Inc.