An American scientist, Stewart Nozette, with access to the details of much U.S. military technology, was recently arrested and charged with trying to sell classified data to Israel. In this case, Israel was not involved, as the "Israeli agent" was an FBI agent pretending to be one. Nozette had been under suspicion of selling American secrets overseas, and had mentioned to a colleague that if the U.S. government ever tried to prosecute him, he would flee to Israel and "tell them everything" he knew about classified U.S. technology.
Israel has long spied on the U.S., and this came to a head in the 1980s when U.S. government employee Jonathan Pollard was convicted of passing large quantities of American secrets to Israel. Some of this stuff was later sold or traded to other foreign nations by Israel. Pollard is serving a life sentence, and Israel is constantly trying to get him freed. As a result of the Pollard case, Israel promised to stop spying on the U.S. But American intelligence agencies believe that Israeli espionage operations against the U.S. have not stopped, but have just become far more discreet.