EXCLUSIVE: The Case for Israel's Strike on Syria

Oct. 19, 2007— -- Israeli officials believed that a target their forces bombed inside Syria last month was a nuclear facility, because they had detailed photographs taken by a possible spy inside the complex, ABC News has learned.

The Bush administration has steadfastly refused to say anything about the Israeli raid on Syria, or to confirm what was hit. But ABC News has learned of the apparent mole and other dramatic and secret details about the events leading up to the airstrike, plus the evidence that supported it.

A senior U.S. official told ABC News the Israelis first discovered a suspected Syrian nuclear facility early in the summer, and the Mossad — Israel's intelligence agency — managed to either co-opt one of the facility's workers or to insert a spy posing as an employee.

As a result, the Israelis obtained many detailed pictures of the facility from the ground.

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The official said the suspected nuclear facility was approximately 100 miles from the Iraqi border, deep in the desert along the Euphrates River. It was a place, the official said, "where no one would ever go unless you had a reason to go there."

But the hardest evidence of all was the photographs.

The official described the pictures as showing a big cylindrical structure, with very thick walls all well-reinforced. The photos show rebar hanging out of the cement used to reinforce the structure, which was still under construction.

There was also a secondary structure and a pump station, with trucks around it. But there was no fissionable material found because the facility was not yet operating.

The official said there was a larger structure just north of a small pump station; a nuclear reactor would need a constant source of water to keep it cool.

The official said the facility was a North Korean design in its construction, the technology present and the ability to put it all together.

It was North Korean "expertise," said the official, meaning the Syrians must have had "human" help from North Korea.

A light water reactor designed by North Koreans could be constructed to specifically produce plutonium for nuclear weapons.