JERUSALEM -- An Israeli defense official says the head of the American CIA spy agency has made an unannounced visit to Israel.

The official says CIA chief John Brennan met Israeli Defense Minister Moshe Yaalon. He did not disclose other details.

The official spoke Friday on condition of anonymity because he was not authorized to discuss the visit with reporters.

Brennan's trip comes amid Israeli concerns about weapons transfers from Syria to the Lebanon's militant Hezbollah.

Israel has carried out airstrikes aimed at halting arms shipments to Hezbollah.

Israeli Prime Minister Benjamin Netanyahu traveled to Russia this week to persuade Moscow not to sell an advanced air defense system to Syria that could complicate any possible aerial campaign.

Israel is also in close contact with the U.S. over Iran's suspect nuclear program.

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  • US President Barack Obama waves as he arrives at the Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • US President Barack Obama delivers a speech upon his arrival at Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • US President Barack Obama, second right, Israel's prime minister Benjamin Netayahu, right, and Israel' President Shimon Peres, during a welcoming ceremony upon Obama's arrival at Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • President Barack Obama, left, with Israeli Prime Minister Benjamin Netanyahu, right, during his arrival ceremony at Ben Gurion International Airport in Tel Aviv, Israel, Wednesday, March 20, 2013, (AP Photo/Pablo Martinez Monsivais)

  • US President Barack Obama reviews an honor guard upon his arrival at Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • US President Barack Obama, center, Israel's prime minister Benjamin Netanyahu, right, and Israeli President Shimon Peres, second left, laugh as they walk during a welcoming ceremony upon Obama's arrival at Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • President Barack Obama, left, and Israeli Prime Minister Benjamin Netanyahu, right, tour the Iron Dome Battery defense system at Ben Gurion International Airport in Tel Aviv, Israel, Wednesday, March 20, 2013, (AP Photo/Pablo Martinez Monsivais)

  • President Barack Obama and Israeli Prime Minister Benjamin Netanyahu tour the Iron Dome Battery defense system, at Ben Gurion International Airport in Tel Aviv, Israel, Wednesday, March 20, 2013, (AP Photo/Pablo Martinez Monsivais)

  • US President Barack Obama, left, and Israel's Prime Minister Benjamin Netanyahu, walk after a welcoming ceremony upon Obama's arrival at Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • US President Barack Obama speaks with a Muslim clergy man during a welcoming ceremony upon his arrival at Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • U.S. President Barack Obama, right, and Israeli Prime Minister Benjamin Netanyahu take a bite of matzah as they tour the Technology Expo in Jerusalem, Israel,Thursday, March 21, 2013. (AP Photo/Pablo Martinez Monsivais)

  • Palestinians rip an American flag during a protest against the visit of the U.S. President Barack Obama in Gaza City, Wednesday, March 20, 2013. (AP Photo/Adel Hana)

  • Israeli soldiers scuffle with a Palestinian activist wearing a mask of U.S. President Barack Obama during a protest in the West Bank town of Hebron, Wednesday, March 20, 2013. (AP Photo/Bernat Armangue)

  • A Palestinian man holds a poster during a protest against the visit of the US President Barack Obama in the West Bank city of Jenin, Wednesday, March. 20, 2013. (AP Photo/Mohammed Ballas).

  • An Israeli salesman watches the arrival of US President Barack Obama in an electronics store in Ashkelon, Israel, Wednesday, March 20, 2013. (AP Photo / Tsafrir Abayov)

  • A Palestinian activist is detained by Israeli soldiers after a protest in the West Bank town of Hebron, Wednesday, March 20, 2013. (AP Photo/Nasser Shiyoukhi)

  • US President Barack Obama delivers a speech upon his arrival at Ben Gurion airport near Tel Aviv, Israel, Wednesday, March 20, 2013. (AP Photo/Ariel Schalit)

  • US President Barack Obama delivers a speech to the Israeli people at the Jerusalem International Convention Center in Jerusalem, on March 21, 2013 on the second day of his 3-day trip to Israel and the Palestinian territories. (MANDEL NGAN/AFP/Getty Images)

  • US President Barack Obama shields his eyes as he looks up at a person who shouted out during his speech to the Israeli people at the Jerusalem International Convention Center in Jerusalem, on March 21, 2013 on the second day of his 3-day trip to Israel and the Palestinian territories. (MANDEL NGAN/AFP/Getty Images)

  • US President Barack Obama waves as he walks off stage after delivering a speech to the Israeli people at the Jerusalem International Convention Center in Jerusalem, on March 21, 2013 on the second day of his 3-day trip to Israel and the Palestinian territories. (MANDEL NGAN/AFP/Getty Images)

  • U.S. President Barack Obama is welcomed by Palestinian girls during his visit to Al Bera Youth Center March 21, 2013 in Ramallah, the West Bank. This is Obama's first visit as president to the region and his itinerary includes meetings with the Palestinian and Israeli leaders as well as a visit to the Church of the Nativity in Bethlehem. (Alaa Badarneh-Pool/Getty Images)

  • US President Barack Obama, left, shakes hands with Palestinian President Mahmoud Abbas during a joint press conference in the West Bank city of Ramallah, Thursday, March. 21, 2013. (AP Photo/Majdi Mohammed)

  • President Barack Obama waves to media as he walks with Palestinian President Mahmoud Abbas, right, as he arrives at the Muqata Presidential Compound Thursday, March 21, 2013, in the West Bank town of Ramallah. (AP Photo/Carolyn Kaster)

  • Palestinians smoke water-pipes at a coffee shop as U.S. President Barack Obama appears on television in the West Bank city of Ramallah, Thursday, March 21, 2013. (AP Photo/Bernat Armangue)

  • US President Barack Obama shakes hands with Greek Orthodox Patriarch Theopilos III after receiving a gift during a tour the Church of the Nativity, built on the site where tradition says Jesus was born, in the West Bank city of Bethlehem, on March 22, 2013, on the final day of Obama's 3-day trip to Israel and the Palestinian territories. (SAUL LOEB/AFP/Getty Images)

  • In this handout photograph supplied by the Government Press Office of Israel (GPO), U.S. President Barack Obama pays his respects at the grave of Theodore Herzl after Marines layed a wreath on his behalf during a visit to Mount Herzl on March 22, 2013 in Jerusalem, Israel. (Photo by Kobi Gideon/GPO via Getty Images)

  • U.S. President Barack Obama visits the Hall of Names at the Yad Vashem Holocaust Memorial museum with Rabbi Yisrael Meir Lau, Israel's Prime Minster Benjamin Netanyahu, Chairman of the Yad Vashem Directorate Avner Shalev and Israel's President Shimon Peres on March 22, 2013 in Jerusalem, Israel. (Photo by Uriel Sinai/Getty Images)

  • In this handout photograph supplied by the Government Press Office of Israel (GPO), U.S. President Barack Obama pays his respects in the Hall of Remembrance as marines lay a wreath on his behalf during a visit to the Yad Vashem Holocaust Museum with Rabbi Yisrael Meir Lau, Israel's President Shimon Peres, Israel's Prime Minster Benjamin Netanyahu and Chairman of the Yad Vashem Directorate Avner Shalev during a visit to Yad Vashem at Mount Herzl on March 22, 2013 in Jerusalem, Israel. (Amos Ben Gershom/GPO via Getty Images)

  • U.S. President Barack Obama (4R) visits the Church of the Nativity with Palestinian President Mahmoud Abbas (5R) and U.S. Secretary of State John Kerry (5L) on March 22, 2013 in Bethlehem, West Bank. (Atef Safadi-Pool/Getty images)

  • US President Barack Obama (R) hugs Israeli Prime Minister Benjamin Netanyahu (C) alongside Israeli President Shimon Peres prior to departing from Ben Gurion International Airport in Tel Aviv, Israel, on March 22, 2013. (SAUL LOEB/AFP/Getty Images)

  • US President Barack Obama walks down the steps of Air Force One upon his arrival at Queen Alia International Airport in Amman, Jordan, on March 22, 2013. (SAUL LOEB/AFP/Getty Images)

  • US President Barack Obama speaks with Jordan's King Abdullah II (R) during a meeting at Al-Hummar Palace in Amman on March 22, 2013. (SAUL LOEB/AFP/Getty Images)

  • Jordan's King Abdullah II (R) reviews an honour guard with US President Barack Obama during a welcoming ceremony at Al-Hummar Palace in Amman on March 22, 2013. (SAUL LOEB/AFP/Getty Images)

  • A Jordanian activist burns a representation of a U.S. flag, during a protest in front of the U.S. embassy against a visit by President Barack Obama to the kingdom, in Amman, Jordan, Thursday, March 21, 2013. (AP Photo/Mohammad Hannon)

  • U.S. President Barack Obama pays his respects in the Hall of Remembrance in front of Israel's President Shimon Peres, Israel's Prime Minster Benjamin Netanyahu, Chairman of the Yad Vashem Directorate Avner Shalev and Rabbi Yisrael Meir Lau after marines layed a wreath on his behalf during his visit to the Yad Vashem on March 22, 2013 in Jerusalem, Israel. (Photo by Uriel Sinai/Getty Images)

  • Barack Obama

    U.S. President Barack Obama stops to look at the Treasury during his tour of the ancient city of Petra in Jordan, Saturday, March 23, 2013. (AP Photo/Pablo Martinez Monsivais)

  • Barack Obama

    U.S. President Barack Obama looks up during his tour of the ancient city of Petra, Jordan, Saturday, March 23, 2013. (AP Photo/Pablo Martinez Monsivais)

  • U.S. President Barack Obama shakes hands with King Abdullah II of Jordan as he departs Queen Alia International Airport in Amman, Jordan, Saturday, March 23, 2013. (AP Photo/Pablo Martinez Monsivais)