North Korea’s new ambassador to Cuba has officially begun his duties, according to Cuba’s Presidential Office on Thursday, amid signs of strain in the two countries’ longtime partnership.

Han Su Chol presented his credentials on Thursday to Cuban Vice President Salvador Valdés Mesa and Foreign Minister Bruno Rodríguez Parrilla.

Valdés Mesa said that North Korea is a “sister nation” to Cuba, with which Cuba “shares a long history of struggle against imperialism, our common enemy.” 

“[North] Korea will always be able to count on Cuba,” the Cuban vice president told Han, according to the country’s presidential office. 

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