"Welcome, welcome to 1800 Online!" says presenter Lizandra Díaz Blanco at the start of Radio Martí's popular interview and call-in show 1800 Online. A few clicks away, TV Martí streams live from the network's website, with a daily diet of news, comedy and Major League Baseball games – all of it in Spanish, and all directed at an audience in Cuba.

After more than half a century of mutual enmity and distrust, Cuba and the United States are poised finally to restore full diplomatic relations. Foreign ministers Bruno Rodríguez and John Kerry will meet in Washington on Monday to mark the reopening of Cuba's embassy to the United States. The Cuban flag will once more hang in the lobby of the State Department.

"We are in the front seat of a very important moment in history," said Carlos García Pérez, director of Martí Noticias, in April, when he addressed the Broadcasting Board of Governors, which oversees all US-funded international news. "More than ever the Martís need to provide Cuba free flow of information so that our audience can make informed decisions as to their future."

But several obstacles remain in the path to fully normalized relations: a broad economic and travel embargo is still in place, and president Raúl Castro has called again and again for the return to Cuban sovereignty of the US naval base at Guantánamo Bay.

He has also repeatedly insisted that the US close down Radio and TV Martí.

And as relations improve, the stations – which have cost Congress more than $700m during the last three decades – are under pressure to show they are truly effective at providing Cubans with access to a free press.