The United States and Cuba have reached a deal to reopen embassies in Washington and Havana, in a major step toward ending decades of Cold War enmity.
President Barack Obama is expected to issue a statement at 11:00 am (15:00 GMT) Wednesday in the White House Rose Garden about the deal, which constitutes one of the major foreign policy achievements of his presidency.
"We will formally announce tomorrow that the United States and Cuba have reached an agreement to re-establish formal diplomatic relations and open embassies in each other's capitals," a US official said.
Diplomatic ties have been frozen for five decades.
From the Bay of Pigs invasion to the Missile Crisis, antagonism across the narrow Straits of Florida often threatened to turn the Cold War hot.
Both countries are currently represented by "interest sections," formally part of the Swiss embassy.
The current head of the US interests section in Havana, Jeffrey DeLaurentis, is expected to deliver a message on reopening embassies from Obama to Cuban President Raul Castro on Wednesday.
But after 18 months of secret negotiations by aides, it was Obama and Castro who agreed in December to restore relations.
The pair held a historic meeting in Panama in April -- the first sitdown between US and Cuba leaders since 1956.
In May, the United States paved the way for further rapprochement by taking Cuba off the list of state sponsors of terrorism.
Havana had vehemently protested its 1982 inclusion on the blacklist, which hampered its access to global markets.
Polls show a majority of Americans support Obama's efforts to improve ties.
But the island is still subject to a US trade embargo put in place in 1962.
There is fierce opposition to lifting the embargo from Republican lawmakers.
Republican presidential hopeful Jeb Bush on Tuesday said the move to open a US Embassy in Cuba was a bad idea.
"This July 4, reports of a new US embassy in Havana will legitimize repression in Cuba, not promote the cause of freedom and democracy."
In the meantime, other vestiges of ideological animosity are rapidly receding into history.
Travel and communications restrictions between the two countries have been significantly eased.
An American orchestra has toured Cuba for the first time in decades, and Airbnb has even established a foothold on the Communist Party-ruled Caribbean Island.
The White House has said that a presidential visit is possible before Obama leaves office in 2017.
Latin American allies have hailed thawing US-Cuba ties as transformative for Washington's role in the region.
Visiting Washington on Tuesday, Brazilian President Dilma Rousseff described better US-Cuba relations as "a very decisive milestone and point in time in US relations with Latin America."
"It is really about putting an end to the last lingering vestiges of the Cold War, and it ultimately elevates the level of the relations between the US and the entire region," she said.
She described Obama's move as a "gesture to all of Latin America and also to world peace at large. It is an important example of relations to be followed."