U.S. prosecutors charged an Indian man with attempting to assassinate an American citizen on U.S. soil, a dramatic improvement that threatens to trigger new rifts within the deepening relationship between the U.S. and India, a key ally. 

In an indictment unsealed Wednesday, prosecutors stated Nikhil Gupta paid somebody he thought was a success man $100,000 to homicide the goal, Gurpatwant Singh Pannun, an advocate for carving out an unbiased Sikh homeland from the north Indian state of Punjab.