Since 2009, the National Security Agency (NSA) has been sharing raw signals intelligence (SIGINT), including information about specific US people, directly with Israel’s counterpart to the NSA, The Guardian reported on Wednesday. The British newspaper’s revelation comes once again from the documents provided by former NSA contractor Edward Snowden to American journalists Glenn Greenwald and Laura Poitras.

According to the five-page memorandum of understanding, the agreement appears to be a one-way street. Israel, at least as far as this document is concerned, is not obligated to reciprocate.

The raw SIGINT includes “unevaluated and unminimized transcripts, gists, facsimiles, telex, voice, and Digital Network Intelligence metadata and content.” In the context of SIGINT and spycraft, gist is generally assumed to mean something short of a word-for-word transcript.

The agreement stresses Israel's obligations to respect the privacy of US persons and limits the uses of the raw intelligence information. However, the stress on Israeli intelligence needing to respect limits on the data—they weren't allowed to retain data with the identity of US persons for more than one year, for example—suggests just how much private data was shared.

The agreement goes on to acknowledge that the US has longstanding intelligence-sharing agreements with the four other members of the “Five Eyes” alliance: the United Kingdom, Canada, New Zealand, and Australia. Israeli intelligence must apply the same procedures to persons from those countries that it applies to US persons.

The document is something of a "gentleman's agreement," not legally enforceable as a treaty.

“This agreement is not intended to create any legally enforceable rights and shall not be construed to be either an international agreement or a legally binding instrument according to international law.”

The NSA knew that the Israelis might be looking at information about US citizens—but they wanted to make sure that US government employees weren't snooped on.

According to the document, Israel must immediately destroy any communication that is “to or from an official of the US Government,” including anyone from the executive, legislative, or judicial system, “independent of seniority or position.”

Despite the cooperation, Israel is viewed as more of a "frenemey" than a close ally. The Guardian also quoted from, but did not publish, what it described as “another top secret document” from 2008, where a “senior NSA official points out that Israel aggressively spies on the US.”

"On the one hand, the Israelis are extraordinarily good Sigint partners for us, but on the other, they target us to learn our positions on Middle East problems," the official is quoted as saying. "A NIE [National Intelligence Estimate] ranked them as the third most aggressive intelligence service against the US.

"One of NSA's biggest threats is actually from friendly intelligence services like Israel. There are parameters on what NSA shares with them, but the exchange is so robust, we sometimes share more than we intended."