The Boston Marathon bombers had planned to detonate their remaining explosives in New York City's Times Square, law enforcement officials told US network NBC News.
Dzhokhar Tsarnaev had initially told questioners in hospital that he and his brother were planning to go to New York to "party", but later changed his story to say they wanted to explode more bombs.
One senior official told NBC News that the Tsarnaev brothers' plan was "undeveloped and aspirational at most."
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