Barack Obama opened an extraordinary visit to Cuba on Sunday, the first by a sitting U.S. president in nearly 90 years.

Obama's three-day trip is a crowning moment in his ambitious effort with Cuban President Raul Castro to restore normal relations between their countries.

On Monday, Obama is scheduled to meet with Castro. On Tuesday, he is to attend a Major League Baseball exhibition game between the Tampa Bay Rays and Cuba's National Team. 

But some Cuban dissidents, human rights observers and politicians have spoken of their concern over Obama's visit.

"It is totally unacceptable for the president of the United States to reward a dictatorial regime," U.S. Sen. Robert Menendez told reporters in Newark, N.J. 

Ahead of Obama's arrival, counter-protesters and police broke up an anti-government demonstration by the Ladies in White group, whose members were taken into custody by female police officers in a scene that plays out in Havana each Sunday. 

What do you think of Obama's visit to Cuba? Here's how the conversation went: 

"Clearly just an opportunity to exploit a 'new frontier' physically nearby the U.S. Anyone who thinks that open relations with the U.S. equates with improved standard of living need to look at pretty well any other Caribbean or Central American country (with some exceptions). That said, anyone taking the moral high-ground on building relations with dictators/authoritarian regimes needs to take a look at our love for China, among others, and remember that international relations is just about helping business at any cost." — unknown 

"Wife and I spent two weeks touring Cuba by private taxi and local bus in 2015.  As I told our guide (a 34-year-old medical doctor), thawing of relations with the U.S. will be to the benefit of Cuba but is not without its risks and hazards. His stated greatest fear was the inevitable loss of Cuba's educated class to better economic opportunities elsewhere and the resultant drag on social and economic development. Even now Cuba loses many of its doctors and engineers to other Latin American countries. Any major sea change like this will require careful and skilled management to be successful without turning into a disaster for the people of Cuba. American corporations have little down side by contrast." — Tootsall

"This is a mistake. This will only benefit the Corporations. They need a new market and this is one of the few left. Profit and greed." — Ralph Gould

"In my opinion, Obama's visit to Cuba is a historic opportunity in the aspect of boarder security, Trade, stability in the region, and overall end to the Cold War aria. Cuba is not in essence an ally of America but eventually all disagreements will be solved and this visit is a crucial step to that solution." — Nathaniel Black 

"This is a historic and momentous opportunity. Fifty years of isolation achieved next to nothing. I am certain and active engagement and increased trading/cultural/tourist ties will achieve far more in a far shorter period of time." — Brad Grundy

"The bigger mistake by far would be to continue undermining the future of the Cuban people with a stupid embargo, the act of aggression of the world's richest country against a poor country for stupid ideological reasons. The U.S. has to deal with a host of oppressive states, take your pick and for the grossest of reasons, economics trumping human rights." — J. Seth 

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