"Syria was on the U.S. nuclear watch list," a senior U.S. official told the Associated Press on Friday, asserting that foreign technicians were in the country and that there had been possible contacts with suppliers for nuclear equipment.

Andrew Semmel, acting deputy assistant secretary for nuclear nonproliferation policy, didn't name the suppliers, but said there were North Koreans in Syria and that he couldn't exclude that the network run by disgraced Pakistan nuclear scientist A.Q. Khan was possibly involved.

Semmel was responding to questions about an alleged Israel Air Force airstrike in northern Syria last week. Neither side has explained what exactly happened, but a U.S. government official confirmed that Israeli warplanes were targeting weapons from Iran and destined for Hezbollah militants in Lebanon.

"There are indicators that they do have something going on there, he said," Semmel said. "We do know that there are a number of foreign technicians that have been in Syria. We do know that there may have been contact between Syria and some secret suppliers for nuclear equipment. Whether anything transpired remains to be seen."...

...Asked if the suppliers could have been North Koreans, he said: "There are North Korean people there. There's no question about that. Just as there are a lot of North Koreans in Iraq and Iran."

Asked if the so-called Khan network, which supplied nuclear technology to Iran, Libya and North Korea, could have been involved, he said he wouldn't exclude it...

...The former U.S. ambassador to the United Nations, John Bolton, said North Korea may be using Syria and Iran as "safe havens" for its nuclear activity, and another U.S. official was quoted as saying Damascus may be building a nuclear facility with North Korean assistance.

Bolton recently told Haaretz that United States President George W. Bush warned North Korea last year against transferring nuclear material to Syria, Iran or a terrorist organization, saying such a move would be perceived as a "grave threat."...

...Syria said Friday that there would be no military response to the incident. Damascus protested Tuesday to the United Nations about the strike...