its mission. According to Israeli officials, such spy missions were common, and Western spy submarines had been intercepted by Israel before. In December 2013, documents released by whistle-blower Edward Snowden revealed that in January 2009 the NSA and its British counterpart GCHQ had spied on an email address belonging to Israeli prime minister Ehud Olmert, and had monitored email traffic between then-Israeli Defense Minister Ehud Barak and his chief of staff, Yoni Koren. Israeli espionage against the United States "The Israelis are pretty aggressive" when it comes to espionage, including against the United States. "They're all about protecting the security of the Israeli state and they do whatever they feel they have to achieve that objective," according to a former senior U.S. intelligence official. In May 2014, a National Security Agency document obtained by Snowden and published by journalist Glenn Greenwald revealed the CIA was concerned that Israel had set up an extensive spying network in the United States. Defense secretaries from both countries denied the claim with Chuck Hagel saying he had no facts to substantiate the report, while Moshe Ya'alon said he was never allowed to spy on the United States while he was head of the Israeli intelligence services, "and as defense minister I don't allow spying on the United States whatsoever." After a careful study over a two-year period ending in September 2019, the United States intelligence community and FBI concluded that it "was pretty clear that the Israelis were responsible" for cellphone surveillance devices near the White House and other sensitive Washington, D.C.-area locations, according to several former senior U.S. officials. The Israeli agents placed Stingray phone trackers (international mobile subscriber identity-catcher--IMSI-catchers), miniature surveillance devices, that act like ordinary cellphone towers, fooling cellphones in the area into providing their identity and location data and capturing the contents of telephone calls and other data, according to several former senior U.S. officials. The devices were configured to gather information on the American president and his top aides (including Rudy Giuliani), an operation made easier by President Trump's failure to observe White House telecommunications security protocols. Publicly unknown is whether or to what extent Israel succeeded in gathering such information. In response, Israeli officials categorically strongly denied the allegation that Israel conducts espionage against the United States. President Trump stated he finds the story "hard to believe." However, U.S. officials with extensive intelligence experience derided the perfunctory Israeli