American president Barack Obama has touched down in Cuba for a historic three-day visit to the communist-ruled island.
The visit is the first by a sitting US president since Calvin Coolidge went there 88 years ago and follows decades of animosity between the former Cold War foes.
A Cuban foreign ministry official Josefina Vidal said her government was prepared to discuss every issue during the trip.
But she insisted matters such as human rights and democracy will not be negotiated.
"There are no policies that have to be dismantled in Cuba in order to advance towards the normalisation of relations with the United States. It's different in the case of the United States because for many years they have been adopting policies that have been hostile towards Cuba."
Mr Obama has just been welcomed at Havana's airport.
Earlier, Cuban police backed by hundreds of pro-government demonstrators broke up the regular march of the dissident group Ladies in White, detaining about 50 people hours before Mr Obama's arrival.
The women and their male supporters were pulled into police vans after they sat down to block a Havana street where the pro-government protesters shouted slogans at them.
A similar scene plays out every Sunday as the Ladies In White take to the streets to protest against political repression in Cuba. They are usually released after a few hours.
This time the protest was more intense than usual, given Mr Obama's impending visit.