The Cuban flag was raised over Havana’s newly-restored embassy in Washington on Monday as the US and Cuba resumed diplomatic ties frozen for half a century.

Cuban Foreign Minister Bruno Rodriguez presided over the re-inauguration of the embassy, a milestone in the diplomatic thaw that began with a breakthrough announcement by U.S. President Barack Obama and Cuban President Raul Castro on Dec. 17.

“A new stage will begin, long and complex, on the road toward normalization,” Cuban President Raul Castro said in a televised address last week to the Cuban people. “Which will require the will to find solutions to the problems that have accumulated over more than five decades and hurt ties between our nations and peoples.”