JERUSALEM, March 21 (Xinhua) -- Israel's military on Wednesday went public for the first time about an air attack that destroyed a nuclear reactor in Syria in 2007, confirming the strike was planned and carried out by Israel.

Early on Wednesday morning, the Israeli censor lifted an 11-year-old ban, revealing that Israel sent F-15 and F-16 warplanes in an overnight operation to bomb a partially-completed nuclear facility in al-Kubar near Deir ez-Zor, 450 km northeast of Damascus.

Israel has long been widely believed to stand behind the secret mission, dubbed by the army "outside the box," but Wednesday's announcement was the first time it officially confirmed its involvement.

Declassified surveillance photographs, footages, and maps, released by the army, show a box-like building in a desert area, which Israel's intelligence identified as a nuclear reactor that could become operational within months.

A military spokesperson said in a statement that the reactor posed "a nuclear threat against the State of Israel and the entire region."

Two groups of aircrafts took off from a military airbase in Israel at 22:30 (20:30 GMT) and flew low to stay undetected, according to the statement. They attacked at 00:45 (22:45 GMT.)

"The whole operation took four hours," the military said. "The Military Intelligence Directorate estimated that the nuclear facility was damaged beyond repair."

Preparations for the attack spanned over two years, in which officials in the Military Intelligence Directorate had been monitoring the project.

The new documents show that the Israeli intelligence estimated that the facility would become active toward the end of 2007.

"The Air Force had very little time to prepare the attack and account for possible contingencies, such as retaliation by the Syrian forces," the military said.

"Once the attack plan was ready, however, it was possible to execute it within 12 hours from the moment the order was to be given."

The army hinted it used also U.S. intelligence information and according to the Hebrew-language Ha'aretz newspaper, Israel told the United States about the planned attack in advanced.

Israel did not say why it chose to publish the information about the attack.

The declassification of the mission could be related to a memoir that former Prime Minister Ehud Olmert, who approved the operation in his former capacity, had written during his time in prison. Olmert was recently freed after serving a 14-month sentence for corruption offenses.

His manuscript reportedly includes a chapter describing the mission and Olmert's part in it. Olmert's lawyer said the entire manuscript was sent to the censor for its approval to publish classified information.

The declassification comes also amidst repeated calls by Prime Minister Benjamin Netanyahu for the United States and the international community to take a more aggressive action to stop Syria's ally, Iran, from establishing a foot in Syria.

Netanyahu warned on several different occasions that Israel will not allow an Iranian presence on the ground of its northern neighbor, although he did not say what steps Israel considers to take should Iran establish permanent military bases in the war-torn country.

Israeli Intelligence Minister Israel Katz said the attack should serve as a warning to Iran. "The successful operation... sends a clear message: Israel will never allow nuclear weapons to countries like Iran who threaten its existence."

Israel's Chief of Staff Gadi Eizenkot, who served as commander of the Northern Command during the operation, said: "The lesson from the 2007 attack on the reactor is that the State of Israel will not accept the establishment of a capability that constitutes an existential threat to Israel. This is the message to our enemies in the near and far future."