U.S. and Cuban officials welcomed the first day of their historic diplomatic talks in Havana on Wednesday as "productive" and "constructive" despite lingering differences over migration issus.

The first of two days of talks aimed at ending decades of Cold War enmity focused on migration.

From fruit sellers to artists drawing Havana cityscapes, Cubans are hopeful that Wednesday's highest-level U.S. government visit in 35 years will shed Cold War-era rivalries and improve their daily lives.

The U.S. delegation will arrive in Havana following the historic decision by U.S. President Barack Obama and Cuban leader Raul Castro in December to seek normal diplomatic relations.

A Russian intelligence warship docked in Havana on Tuesday, a day before the start of historic U.S.-Cuba talks aimed at normalizing diplomatic relations.

There was nothing stealthy about the arrival of the Viktor Leonov CCB-175, which was moored to a pier in Old Havana where cruise ships often dock. But the visit was not officially announced by Cuban authorities.

The high-fenced U.S. Interests Section on Havana's postcard-pretty seafront was a symbol of the Cold War friction that is now finally dissipating as it prepares to become an embassy.

Transforming the concrete and glass mission into an embassy will be a central part of historic negotiations between U.S. and Cuban officials this week aimed at restoring diplomatic relations.

U.S. lawmakers visiting Havana voiced hope Monday that historic talks between U.S. and Cuban officials this week will mark a "new era" of relations, ending decades of Cold War-era hostility.

The six-member delegation of congressional Democrats, led by Senator Patrick Leahy, met Foreign Minister Bruno Rodriguez as well as dissidents and Cardinal Jaime Ortega during their two-day visit.

A total of 63 percent of Americans approve of recent moves by the United States and Cuba to restore diplomatic ties and two-thirds favor lifting the economic embargo altogether, a survey released Friday said.

Despite those assessments, only 32 percent of Americans think that the warming of ties between the Cold War-era foes will lead to more democracy in Cuba, the Americas' only communist state, according to the Pew Research Center report.

The United States will ease travel and trade restrictions with Cuba on Friday, marking the first concrete steps towards restoring normal ties with the Cold War-era foe since announcing a historic rapprochement.

While full-fledged tourism to Cuba remains prohibited, certain approved categories of Americans, like journalists, scholars, artists and athletes will face fewer bureaucratic hurdles to travel to the Communist-ruled nation under the new rules.

Cuba has freed all 53 political prisoners agreed to in last month's normalization deal with the United States, the U.S. State Department said Monday.

News of the release comes as U.S. officials prepare to travel to Havana next week for talks to lay the foundation for a historic rapprochement after a half-century of Cold War enmity.

Dissidents in Cuba keen to get off the sidelines are reeling after the United States and the communist government here said they will seek to end decades of Cold War bad blood.

Following news of the historic shift, announced December 17, many members of illegal opposition groups were riled by what they see as a U.S. failure to get Havana to make specific pledges on human rights before seeking a new relationship.

Cuba Friday denied reports it had summoned foreign media to a press conference amid reports that 88-year-old Fidel Castro's health is deteriorating.

Such press conferences are always convened by emails or cell phone text messages and none have been sent, said an official at the International Press Center, the Foreign Ministry section that deals with foreign media.