The US broke diplomatic relations with Cuba on January 3, 1961, formally due to a disagreement about staffing levels at the respective Embassies.

Both under the Swiss and later with US staff, the Section has occupied the former United States Embassy building on Havana's Malecon which was designed by Harrison & Abramovitz architects and originally entered into service in 1953.

When relations were broken in 1961, the building was occupied, and its contents safeguarded, by the Swiss Embassy personnel who handled US Interests in Cuba on behalf of the US Government as the protecting power until the arrival of the US staff in 1977.

The Swiss staff included some of the Foreign Service national employees (Cuban citizens) who were working at the US Embassy when relations were broken.

The initial American staffing of the Section consisted of ten State Department Officials and a plain clothes US Marine guard detachment.