"Cuba's Council of State has declared official mourning due to the passing of comrade Kim Jong-Il," an official statement said on Monday, noting that Cuba's flag would be flown at half-mast on Tuesday, Wednesday and Thursday.
Cuba and North Korea are among the world's five communist nations.
And Cuba is the only one-party communist regime in the Americas. On North Korean state television on Monday, a tearful announcer delivered the news of Kim's demise at 69 from a heart attack.
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Pyongyang urged service personnel and citizens to rally behind Kim's youngest son Jong-Un, who is in his late 20s.
Last year, he was made a four-star general and given top ruling-party posts despite having had no public profile.
