Which US law extended the longtime US embargo against Cuba?

The Helms-Burton Act, formally known as the Cuban Liberty and Democratic Solidarity (LIBERTAD) Act of 1996, strengthened and made permanent the economic embargo against Cuba that had begun in the early 1960s. This law not only reinforced the restrictions already in place but also expanded them by introducing new provisions. For instance, it included measures that allowed U.S. nationals to sue foreign companies that were using property that was confiscated from them during the Cuban Revolution. The act was designed to promote a transition to a democratic government in Cuba and deter foreign investment in the country.

The other options reflect different legislative measures that do not pertain to the U.S. embargo against Cuba. For example, the McCarran Act primarily focused on internal security and immigration matters, while the National Security Act reorganized U.S. military and intelligence agencies during the Cold War. The Voorhis Act, on the other hand, dealt with issues related to the registration and regulation of foreign agents. Therefore, the Helms-Burton Act stands out as the key legislation aimed specifically at extending and solidifying the embargo against Cuba.