Updated

The first of six Patriot missile batteries being deployed to Turkey to protect against attack from Syria was declared operational and placed under NATO command, the international organization said Saturday.

The battery, provided by the Netherlands, is meant to protect the city of Adana by shooting down missiles that could come over the Syrian border. Turkey has become a harsh critic of the regime in Syria, where a vicious civil war has left at least 60,000 people dead.

The United States, Germany and the Netherlands are providing two batteries each of the latest version of the U.S.-made Patriots. The other five Patriot batteries are expected to be in place and operational in the coming days in Adana, Kahramanmaras and Gaziantep.

"This is a clear demonstration of the agility and flexibility of NATO forces and of our willingness to defend Allies who face threats in an unstable world," Admiral James Stavridis, NATO's Supreme Allied Commander for Europe, said in a statement.

NATO reiterated Saturday that the Patriots are for defensive purposes only. Syria has not fired any of its surface-to-surface missiles at Turkey during its nearly two-year civil war and its government has described the NATO deployment as a provocation.

NATO also deployed Patriot batteries to Turkey during the U.S.-led invasion of Iraq 10 years ago. They were never used and were withdrawn a few months later.

Ali Akbar Velayati, an aide to Iran's supreme leader Ayatollah Ali Khamenei, said Saturday that any attack on Syria would be deemed an attack on Iran, a sign that Tehran will do all it can to protect embattled Syrian President Bashar Assad.

Iran is Syria's strongest ally in the Middle East, and has provided Assad's government with military and political backing for years. In September, the top commander of Iran's powerful Revolutionary Guard, Gen. Mohammad Ali Jafari, said the elite unit had high-level advisers in Syria. Iran also is believed to be sending weapons and money to Syria as it endures its worst crisis in decades.

"Syria plays a very key role in supporting or, God forbid, destabilizing the resistance front," Velayati was quoted by Iran's semiofficial Mehr news agency as saying. "For this same reason, (an) attack on Syria is considered (an) attack on Iran and Iran's allies."

By backing the rebels trying to oust the Syrian leader, the U.S. and Arab states in the Gulf attacked the "golden ring of resistance," Valayati said, referring to the militant groups, Hamas and Hezbollah, and Iran and Syria, which are all anti-American.

Turkish Prime Minister Recep Tayyip Erdogan, interviewed on Turkish television late Friday, said the Syrian opposition now controls some 70 percent of Syria.

"If you ask me if Bashar is able endure much longer, I say, Bashar is walking, propped up from behind," said Erdogan, who was a close ally of Assad's until the crisis began. "He is losing the support of the Syrian people every day."

"At the moment Damascus is under siege. Aleppo is to a great degree already under the hands of the opposition. In other words, I can say that some 70 percent of the country is under the control of the opposition," Erdogan said.

In the Turkish capital, Istanbul, members of the Syrian opposition gathered Saturday to kick-off a conference aimed at establishing a transitional justice system in Syria after the fall of Assad's regime. The two-day meeting was organized by the U.S.-based Syrian Center for Political and Strategic Studies.

In fighting on Saturday, Syrian forces clashing with rebels uncovered tunnels they were using to smuggle weapons and move around Daraya, a strategic suburb of the capital, Damascus, the state-run news agency said.

Syrian troops have been trying to capture Daraya for weeks, but have faced strong resistance from hundreds of rebels who have used Damascus suburbs to stage attacks on nearby government facilities.