Turkey revealed to Iran the identities of up to 10 Iranians working for the Mossad in Iran, according to a report in The Washington Post on Thursday by columnist David Ignatius.
According to sources quoted in the report, relations between Israel and Turkey had so deteriorated early last year that Turkish Prime Minister Recep Tayyip Erdogan gave the order to "shop" Israeli agents to Iran.
The spies in question were Iranian nationals who would meet with their Mossad handlers inside Turkey. The Turkish-Iranian border is relatively easy to cross.
According to Ignatius, Israel and Turkey have cooperated on intelligence for over 50 years, and Israel was blind-sided by the Turkish betrayal, which was described by knowledgeable sources as a "significant" loss of intelligence and "an effort to slap the Israelis."
The background to the incident began with deteriorating relations between Turkey and Israel in 2009, when Erdogan began championing the Palestinian cause and distancing himself from Israel. Then came the May 2010 Mavi Marmara incident, in which Israeli commandos bordered a Turkish vessel trying to run Israel's blockade of Gaza. Nine Turks were killed in the ensuing fighting. Turkey, which withdrew its ambassador and suspended joint military exercises with Israel, demanded an apology from Israel.
Israel refused to apologize for the incident, claiming that the commandos were justified in boarding the vessel, and that the Turks were killed in self-defense.
According to Ignatius, "U.S. officials were never sure whether the Turkish disclosure was done in retaliation for the flotilla incident or was part of a broader deterioration in Turkish-Israeli relations."
Already in July 2010, then-Defense Minister Ehud Barak had voiced concern that once-stalwart ally Turkey could share Israeli intelligence secrets with Iran. In a closed-door briefing to Israeli community leaders at a kibbutz outside Jerusalem, Barak called Hakan Fidan, the new head of Turkey's National Intelligence Organization, a "friend of Iran."
Ignatius cites an incident several years ago, in which Israeli intelligence officers, speaking to their CIA counterparts, described Fidan as the Iranian Intelligence and Security Ministry's "station chief in Ankara."
"There are quite a few secrets of ours [entrusted to Turkey] and the thought that they could become open to the Iranians over the next several months, let's say, is quite disturbing," Israel's Army Radio quoted Barak as saying in the speech.
Appointed in May 2010, Fidan was previously a foreign policy adviser to Erdogan, whose AK party has roots in political Islam and has often censured Israel. Turkish sources say Fidan has also helped to mediate between the West and Iran over Tehran's disputed nuclear program.
Israel's Mossad spy agency was widely reputed to have helped Turkey to capture PKK leader Abdullah Ocalan in 1999, though then-Mossad chief Efraim Halevy denied involvement.
Israeli Prime Minister Benjamin Netanyahu finally apologized to Erdogan in March 2013, at the urging of U.S. President Barack Obama. But top Israeli officials say relations with Turkey are still tense.
Despite the exposure of the Israeli spy network, Ignatius writes, U.S. Turkish relations have warmed in the past year. According to Ignatius, the U.S. continued to deal with Fidan on sensitive matters.