By Jeff Franks
HAVANA (Reuters) - Former President Jimmy Carter, returning to Cuba for the first time since a groundbreaking 2002 trip, began a three-day visit on Monday to discuss troubled U.S.-Cuba relations and is likely to talk about the fate of imprisoned U.S. aid contractor Alan Gross.
Although just 90 miles of water separate the two Cold War enemies, Carter, 86, is the only U.S. president, former or sitting, to visit the communist-ruled island since a 1959 revolution toppled a U.S.-backed dictator and put Fidel Castro in power.
Carter and his wife Rosalynn, who were invited by the Cuban government, received a low-key welcome from Foreign Minister Bruno Rodriguez after their plane landed at Havana's Jose Marti International Airport on a visit being described as "private".
Rodriguez shook Carter's hand and gave Rosalynn Carter flowers. They continued on with only a wave to the media.
In 2002, Carter was welcomed by then-president Fidel Castro. Now 84, Castro stepped down as president three years ago and was succeeded by his younger brother Raul 79.
Carter was scheduled to go on Monday to the headquarters of Cuba's Jewish community, then meet with Cardinal Jaime Ortega, the Roman Catholic Archbishop of Havana.
He was to hold talks with President Raul Castro on Tuesday.
Carter is expected to discuss the possible release of Alan Gross, 61, who this month was sentenced to 15 years in prison for providing illegal Internet access to Cuban dissidents under a controversial U.S. program.
The Gross case has strained U.S.-Cuba relations after a modest warming under President Barack Obama.
Since leaving office after his 1977-1981 term, Carter has occasionally served as an unofficial diplomatic troubleshooter, including a mission last August to North Korea to secure the release of an American imprisoned there.
"PRIVATE, NON-GOVERNMENTAL MISSION"
The Carter Center in Atlanta said this trip was a "private, nongovernmental mission" for Carter to learn about Cuba's new economic policies and discuss ways to improve U.S.-Cuba ties.
Cuba is preparing for a Communist Party congress in mid-April to approve reforms to the island's Soviet-style economy.
Carter, winner of the Nobel Peace Prize in 2002, may only try to lay the groundwork for Gross' release because Cuban officials reportedly have told him not to expect to take the American home when he leaves on Wednesday.
Gross, jailed since his arrest in Havana on December 3, 2009, was working under a U.S. program promoting political change on the island. Cuba says the program is subversive.
The case has angered the U.S. government, which contends Gross was in Cuba only to provide Internet access to Jewish groups and committed no crime.
Many think Cuba may be open to freeing Gross soon because it has made its point about the U.S. pro-democracy program and because of humanitarian concerns, in that Gross' 26-year-old daughter and 88-year-old mother are both suffering from cancer.
Gross has the right to appeal his conviction to Cuba's highest court, but it is not known if an appeal has been filed.
During his one term in office, Carter took the most significant steps yet to improve U.S.-Cuba relations.
In his 2002 visit, he urged Washington to end its long trade embargo against Cuba. He also called for democracy and better human rights in Cuba and boosted dissidents by publicly mentioning their movement.
The Castros complain regularly that Obama has done little to help relations, despite his stated desire to seek a "new beginning" with Cuba.
Obama has eased U.S. travel restrictions to Cuba, allowed a free flow of remittances to the cash-strapped island and initiated new talks on migration and postal service issues.
Cuba has released most of its political prisoners and is modernizing its economy, but Obama has said it must do more, including the release of Gross, if it wants better relations.
(Additional reporting by Nelson Acosta; Editing by Pascal Fletcher and Philip Barbara)