TEL AVIV, Israel — Israel's confirmation Wednesday that it was behind the 2007 bombing of a suspected Syrian nuclear facility had a specific intended audience: longstanding enemy Iran.

The airstrike on the al-Kabur site in Deir al-Zor destroyed what was believed to be a nuclear reactor, and had been one of the most secretive Israeli military operations in recent memory. Although Israel was widely believed to have been behind the Sept. 6, 2007, strike, it has never before commented publicly on it.

Intelligence Minister Israel Katz sent "congratulations" to then-prime minister Ehud Olmert for the "decision to destroy the nuclear reactor in Syria eleven years ago."

"The operation and its success made it clear that Israel would never allow nuclear weapons to those who threaten its existence," he said on Twitter. "Syria back then — and Iran today."

Israel is deeply alarmed by Iran's growing regional power and ambitions. Tehran is allied with the government of President Bashar al-Assad in the civil war in Syria— also a longstanding enemy of Israel. Sunni powers in the region, such as Saudi Arabia and the United Arab Emirates, are also deeply suspicious of Iran's nuclear ambitions, which they claim have not been curbed by a landmark 2015 international agreement that saw some international sanctions lifted.

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Israeli Defense Minister Avigdor Lieberman underlined intelligence minister Katz's statement.

"The motivation of our enemies has grown in recent years, but so too the might of the ... Israeli Defence Forces," he said in a statement. "Everyone in the Middle East would do well to internalize this equation."

A combination image of what the Israeli military describes is before and after an Israeli air strike on a suspected Syrian nuclear reactor site near Deir ez-Zor. IDF / Reuters

In a lengthy release, the Israeli military said that eight F-15 fighter jets carried out the top-secret airstrikes against the facility about 300 miles northeast of Damascus, and destroyed a site that had been in development for years and was scheduled to go into operation at the end of 2007.

Amos Yadlin, who was the head of Israeli military's intelligence at the time, told NBC News that a unique intelligence operation in Syria in 2006 led to the conclusion that Israel was "facing a project of a plutonium nuclear reactor which has only one purpose — to produce a nuclear bomb."

"The question was how much time do we have, our accurate answer was that we have six to seven months before it will be hot, and then we moved to the operational planning," said Yadlin, the current head of the Institute for National Security Studies research institute in Tel Aviv. "We understood that we have two goals: No core, no war — destroying the nuclear reactor on one hand, and avoiding a war on the other hand."

Israel and Syria were bitter enemies before the Syrian civil war broke out in 2011. Since the conflict erupted, Israel has carried out well over 100 airstrikes, most believed to have been aimed at suspected weapons shipments destined for the Iranian-backed Lebanese militia, Hezbollah.

An Israeli air strike on a suspected Syrian nuclear reactor. IDF / Reuters

When asked whether he believed the announcement was intended as a message to Iran or Assad-allied Russia, Yadlin said: "It is signaling that when it comes to the very vital interest or the very serious threat to the existence to Israel, Israel is going to act — even if Israel has to act alone."

Israel's announcement comes amid rising tensions in the regions, with Saudi Prince Mohammed bin Salman visiting Washington. On Tuesday, Prince Mohammed said if more wasn't done to prevent Iran from acquiring a nuclear weapon, his country will pursue its own “as soon as possible.”

President Donald Trump, who has forged closer ties with longstanding American ally Saudi Arabia, has long promised to scrap the agreement with Iran that saw Tehran curtail its nuclear ambition in exchange for a lifting of punishing economic sanctions.

In Iran, where the country was celebrating New Year, there was no immediate reaction to Israel's announcement.

Paul Goldman reported from Tel Aviv, and Francis Whittaker reported from London.