The Wall Street Journal reports that White House officials learned last year that Israel was spying on closed-door talks with Iran, which wouldn't have been a problem but for the fact that the Israelis shared what they'd learned with lawmakers.
"It is one thing for the US and Israel to spy on each other," a senior US official briefed on the matter told the Journal. "It is another thing for Israel to steal US secrets and play them back to US legislators to undermine US diplomacy."
Israeli officials denied that they had spied directly on negotiators. From the Journal:
The U.S. and Israel, longtime allies who routinely swap information on security threats, sometimes operate behind the scenes like spy-versus-spy rivals. The White House has largely tolerated Israeli snooping on U.S. policy makers—a posture Israel takes when the tables are turned.
The White House discovered the operation, in fact, when U.S. intelligence agencies spying on Israel intercepted communications among Israeli officials that carried details the U.S. believed could have come only from access to the confidential talks, officials briefed on the matter said.