The United States government summoned Syria's ambassador late Friday to discuss concerns over Damascus' possible nuclear program and support for groups that Washington labels as terrorists, a State Department spokesman said.
Spokesman Gordon Duguid said U.S. officials have asked to meet with Syrian Ambassador Imad Moustapha "to discuss our concerns."
"It's nuclear material that hasn't been declared and Syria has to explain" how it got there, said a senior IAEA official, speaking on condition of anonymity.
Syria insists Al-Kibar is a disused military facility, and that any uranium there could have been from the Israeli bombs.
The U.S. move followed a report by U.N. inspectors Thursday that graphite and more uranium traces were found in samples taken from a Syrian site that Washington says was an almost built graphite nuclear reactor destroyed by Israel in November 2007.
The report by the U.N's International Atomic Energy Agency (IAEA) also mentioned Iran and pointed that it had built up a stockpile of nuclear fuel.
U.N. diplomats said Iran had underreported by a third how much uranium it had enriched but that the IAEA believed the discrepancy was a technical mistake rather than subterfuge.
"The report represents another lost opportunity for Iran as it continues to renege on its international obligations," said White House spokesman Robert Gibbs, echoing earlier comments by the State Department.
The report from the U.N. nuclear watchdog conceded that, despite six years of intensive investigation, it was no closer to determining whether Iran's disputed nuclear drive is as peaceful as Tehran claims.
Meanwhile, the U.S. envoy to the United Nations, Susan Rice, said in a radio interview later Friday on that the IAEA report "confirms what we all have feared and anticipated which is that Iran ... remains in pursuit of its nuclear program."
"The United States views Iran acquiring an illicit nuclear capacity as a grave threat to ourselves, to the region and indeed to Israel," Rice told National Public Radio.
The U.S. statements came after the hawkish Likud party leader in Israel Netanyahu described Iran as the Jewish state’s main threat after accepting the task of forming a new government in the wake of the close Feb. 20 elections.
"Iran is seeking to obtain a nuclear weapon and constitutes the gravest threat to our existence since the war of independence," he said at a ceremony at President Shimon Peres's official residence.
"The terrorist forces of Iran threaten us from the north," the presumptive prime minister said in reference to Lebanon and Syria, where Israel says Tehran supplies arms to Hezbollah and Hamas.
"For decades, Israel has not faced such formidable challenges.”