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."
More top news
Sheridan Smith won a standing ovation as she returned to the West End stage after claims she was 'drunk' during a performance.
The 'Let Our Kids Be Kids' campaign wants parents to keep their children off school saying they are "over-tested and over-worked".
Nicky Morgan is expected to defend the proposal when she fields questions at the National Association of Head Teachers' annual conference.