Who are the Three Cuban Agents Released in Alan Gross Deal?

The United States is releasing three Cuban agents who have been held in the United States for 16 years on controversial grounds as part of the agreement in the release of Alan Gross, a 65-year old government contractor who left Cuba this morning after five years in prison.

A senior U.S. official said today that the prisoner transfer came up during a phone conversation Tuesday between President Obama and Cuba's current president, Fidel's brother Raul.

And technically, the White House says they didn't trade the three men for Gross, who was released on humanitarian grounds, but actually for a separate U.S. intelligence asset, detained in Cuba for the last 20 years, whom Havana also released Wednesday

So who are the three Cuban men?

They're part of what was originally called the "Cuban Five," a group of agents convicted of espionage in a controversial 2001 trial which found them guilty of spying on anti-Fidel Castro (Raul's brother) groups but not on the U.S. government itself.

They were sentenced altogether to four life terms plus 77 years, and imprisoned in five separate maximum security prisons throughout the United States. The Cuban government and the Five's supporters contended they were in Miami conducting anti-terrorism operations.

Two of the five were released in 2011 and 2014, respectively.

Today, the remaining three -- Hernndez Nordelo, Ramn Labaino Salazar, and Antonio Guerrero Rodrguez, who have most recently been imprisoned together in North Carolina -- will also be released.

The agreement was reached following more than a year of secret back channel talks at the highest levels of both governments.

But not everyone is pleased with the release of the three agents and the moves toward normalized relations between the U.S. and Cuba that the White House also announced Wednesday.

Sens. Marco Rubio, R-FL, and Bob Menendez, D-NJ, have long opposed normalizing relations with Cuba.

Rubio told ABC News this morning that ultimately he wants the U.S. to enjoy full diplomatic relations with the island nation, Rubio's parents' home country, but not right now when there is a Communist regime in power with a litany of human rights abuses.

"None of these things are going to lead to democracy in Cuba. The Cuban government will use all of those to their advantage without creating political opening. And you mark my words five years from now there will be a dictatorship but a much more profitable one," Rubio said.

Rubio also said later he would do everything he could to block Obama's efforts to normalize relations with Cuba.

Menendez was equally critical of the prisoner transfer.

"There is no equivalence between an international aid worker and convicted spies who were found guilty of conspiracy to commit espionage against our nation," he said.