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
The Labour leader has a certain swagger in this election campaign and his team are upbeat. But why?
Police are appealing for help in tracing a family of six who are feared to be travelling to Syria.
A "truly despicable" thief stole from a woman while she suffered a violent epileptic seizure.