President Barack Obama is expected to announce this morning that the United States and Cuba have reached an agreement to re-establish formal diplomatic relations and reopen embassies in each other’s capitals. President Obama proclaimed in December that he wanted to resume full diplomatic relations with Cuba and, after six months of negotiations, the two countries have worked out details of the new embassies. For the first time in over fifty years the Cuban flag wil fly over its embassy in Washington and the U.S. flag will likewise hover over Havana.

The former U.S. embassy in Havana, now known as the U.S. Interests Section, will be reconverted into a fully operating embassy. The seven-story U.S. Embassy building on the Havana waterfront was constructed in 1953. The U.S. closed its embassy when then President Dwight D. Eisenhower broke off diplomatic relations with Cuba in January 1961. The former embassy building opened as the U.S. Interests Section in 1977 under President Jimmy Carter when he tried to re-establish diplomatic relations with Cuba. The State Department estimates that it needs $6.6 million to renovate the building to make it an operating embassy.

Secretary of State John Kerry is expected to travel to Cuba in July to oversee the embassy’s reopening. President Obama is also expected to travel to Cuba before leaving office in January 2017.

However, before it can reopen, the State Department must notify Congress of its intent to reopen the embassy in Havana. Congress then has 15 days to review the notification before the U.S. can open the embassy. Although certain factions in both houses of Congress continue to oppose widening ties with Cuba, there is unlikely to be a serious challenge to the reopening of the U.S. embassy in Havana.