Iran and North Korea are tightening their relations after a lull, defense sources have told Haaretz. Israeli defense officials are concerned about the development, saying it may reflect an expansion of North Korean aid to Iran's nuclear and missile programs.

In May, the Iranian and North Korean foreign ministers met during a conference of the Non-Aligned Movement in Malaysia. It was a rare public meeting of senior officials from the two countries.

Israeli officials believe that Pyongyang is helping Iran develop its military nuclear program, saying that if Iran was only interested in nuclear energy for civilian purposes, Russia's aid on the matter should have sufficed.

A report by a UN team of experts, whose publication is being delayed by Chinese opposition, has criticized North Korea for its relationship with Iran, which essentially violates the sanctions on both countries. The report says North Korea violated the sanctions when it supplied missile technology to Iran. The components were regularly shipped from North Korean to Iran via a third country, the report said.

Last week, Iran conducted a major missile-launching exercise. It said it launched 14 missiles, including the Shihab 3, which can reach Israel. British Foreign Minister William Hague said the missiles were capable of carrying nuclear warheads and the tests were in violation of a UN resolution.

Meanwhile, the new U.S. secretary of defense, Leon Panetta, did not mention the Iranian nuclear problem when listing his priorities at his inauguration last week. He said his top four priorities were retaining American military strength in an era of budget cuts, defeating Al-Qaida, stabilizing Afghanistan and building a true long-term partnership with Iraq.