WASHINGTON — The United States and Cuba have agreed to open embassies in each other’s capitals, the biggest tangible step in the countries’ historic bid to restore ties after more than a half-century of hostilities.

President Barack Obama is expected to announce the agreement today at the White House. The U.S. Embassy in Havana is scheduled to open later this month.

The U.S. and Cuba have been negotiating the re-establishment of embassies following a surprise December announcement that secret talks had led to an agreement to restart diplomatic relations.

For Obama, ending the U.S. freeze with Cuba is central to his foreign policy legacy as he nears the end of his presidency. Obama has long touted the value of direct engagement with global foes and has argued that the U.S. embargo on the communist island just 90 miles south of Florida was ineffective.

Secretary of State John Kerry, who is in Vienna for nuclear negotiations with Iran, is also expected to speak about the embassy openings. Kerry has said previously that he would travel to Cuba for an embassy opening.

Cuba’s Foreign Ministry said Tuesday evening that it would meet with U.S. Interests Section chief Jeffrey DeLaurentis this morning to receive a message from Obama about reopening embassies.

The U.S. cut off diplomatic relations with Cuba in 1961 after Fidel Castro’s revolution. The U.S. spent decades trying to either actively overthrow the Cuban government or isolate the island, including toughening the economic embargo first imposed by President Dwight D. Eisenhower.

Since the late 1970s, the United States and Cuba have operated diplomatic missions called interests sections in each other’s capitals. The missions are technically under the protection of Switzerland, and do not enjoy the same status as embassies.

While the opening of embassies marks a major milestone in the thaw between the U.S. and Cuba, significant issues remain as the countries look to normalize relations. Among them: talks on human rights; demands for compensation for confiscated American properties in Havana and damages to Cuba from the embargo; and possible cooperation on law enforcement, including the touchy topic of U.S. fugitives sheltering in Havana.

Obama also wants Congress to repeal the economic embargo on Cuba though he faces resistance from Republicans and some Democrats. Those opposed to normalizing relations with Cuba say Obama is prematurely rewarding a regime that engages in serious human rights abuses.