When Prince Charles and Camilla arrived in Cuba on Sunday, they made history. Their tour also marked the first time that members of the British royal family officially visited the Caribbean nation.

The royal couple already revealed their Cuban itinerary, which includes a tour of Old Havana and a dinner with President Miguel Díaz-Canel as the host on Monday. On Tuesday, Prince Charles and Camilla will visit a recording studio, as well as meet some Cubans who own classic British cars.

However, the royal couple’s visit raised some eyebrows from politicians in the United States. “Why would the British government want to recognize Juan Guaidó as the new President of Venezuela when we all know the Castro regime is the one propping up Maduro, dictator in Venezuela ... and then at the same time have the Prince, who has unbelievable worldwide influence, go prop up the regime?” US Senator Rick Scott questioned British Prime Minister Theresa May in a letter protesting Prince Charles’ visit.

During President Obama’s administration, the international relationship between the U.S. and Cuba has significantly improved, compared to the Cold War days. However, President Trump has reversed many of his predecessor’s policy toward Cuba and has even imposed trade and travel restrictions that were already abolished by the previous administration.

The U.S. is concerned with Cuba’s interference with Venezuela’s politics. Cuba is accused of propping up Venezuelan President Nicolas Maduro’s disputed regime with Cuban military and intelligence.

Venezuela entered into a political and humanitarian crisis in January when opposition leader Juan Guaidó said that Maduro's re-election last year was illegitimate. Many countries, including the United States, consider Guaidó as the nation’s rightful ruler.

President Maduro, on the other hand, is accusing Guaidó of being the United States’ puppet. The President believes that the U.S. is trying to get its hands on Venezuela’s oil reserves, said to be the largest in the world, through Guaidó.

Analysts believe that Prince Charles and Camilla’s visit to Cuba is the U.K.’s way of warning its ally about not taking extreme measures against the Caribbean nation. American University professor William LeoGrande said that the visit “lend[s] legitimacy to the Cuban government and represent[s] an implicit warning to the United States that hostile actions against Cuba may incur a diplomatic cost with important allies.”

Prince Charles and Camilla Prince Charles, Prince Of Wales, and Camilla, Duchess of Cornwall, arrive in Cuba on March 24, 2019. Analysts believe that the visit also serves as UK's warning to the US. Chris Jackson/Getty Images