CUBA and the US sealed the re-establishment of full diplomatic ties on Wednesday, despite fierce opposition from US Congress rightwingers.
Cuban President Raul Castro and his US counterpart Barack Obama exchanged formal letters confirming the normalisation of relations for the first time since 1961.
“There are those who want to turn back the clock and double down on a policy of isolation,” Mr Obama said at the White House. “But it’s long past time for us to realise that this approach doesn’t work.” Jeffrey DeLaurentis was named as the US ambassador.
While Mr Obama’s policy of detente with Cuba largely enjoys cross-party support in Congress, reactionary members continue to oppose it.
“Relations with the Castro regime should not be revisited, let alone normalised, until Cubans enjoy freedom,” said Republican House Speaker John Boehner.
And Democratic Senator Bob Menendez accused the president of “incentivising a police state to uphold a policy of brutality.”
Mr Obama has asked Congress for $6 million (£3.8 million) to upgrade the current US diplomatic post in Havana.
The House of Representatives appropriations committee approved legislation last month barring work on the embassy unless Mr Obama certifies that Havana is meeting the terms of the 1996 Helms-Burton Act, which aimed for regime change in Cuba and demanded the extradition to the US of suspects such as former Black Panther Assata Shakur.
Elsewhere the historic move has been welcomed.
In South Africa, where the Miami Five — just released from up to 16 years in US prisons — have been greeted as heroes, the ruling ANC called it a “momentous announcement.”