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.