On an historic day in US and Cuban relations, Cuba released U.S. contractor Alan Gross on Wednesday while the U.S. freed three members of the infamous Cuban Five, who spent over 15 years in American jails for espionage.

Gross, a 65-year-old American government contractor, had been imprisoned in Cuba for five years after traveling to the country under a U.S. Agency for International Development program to deliver satellite phones and communications equipment to the island's small Jewish population.

Cuban officials, however, charged him with trying to foment a "Cuban Spring." As a result, he was arrested, convicted and sentenced in 2011 to 15 years in prison for attempting to create an Internet network for Cuban dissidents "to promote destabilizing activities and subvert constitutional order."

According to a senior Obama administration official, Cuba agreed to release Gross on humanitarian grounds, in addition to an unidentified U.S. spy, who has been in a Cuban jail for more than 20 years. At the same time, the United States released three Cubans jailed for 15 years on spying charges.

The developments are being hailed as a sweeping diplomatic shift in U.S. policy toward Cuba since 1961, when the embassy closed and the embargo was imposed, following Fidel Castro's takeover of the Cuban government.

"We are charting a new course toward Cuba," a senior administration official said, reports CNN. "The President understood the time was right to attempt a new approach, both because of the beginnings of changes in Cuba and because of the impediment this was causing for our regional policy."

President Barack Obama also declared that the United States was ending an "outdated approach" after five decades of isolation failed to accomplish the goal of a democratic and prosperous Cuba.

"Neither the American nor the Cuban people are well-served by a rigid policy that's rooted in events that took place before most of us were born," Obama said during a speech, according to NBC News. "It's time for a new approach."

Alan was greeted by his wife, Judy, along with Sen. Jeff Flake and Rep. Chris Van Hollen on a plane that flew him back to the states.