Early Sunday Israeli jets targeted the Syrian military's fortress on Qasioun Mountain, Damascus, causing the most powerful explosions near the capital in more than two years of fighting.

The strike on key command and control structures of the regime lifted the spirits of Syrian rebels, who have recently been pummeled by a regime counteroffensive, but experts believe the move has more to do with the shadow war between Israel and Iran.

“This shouldn’t be seen as Israel intervening on behalf of the rebels or against [Syrian President Bashar al-Assad],” said Jonathan Spyer, a senior research fellow at the Interdisciplinary Center in Israel, told The Times. “This is an escalation in a conflict we know about, and that is the conflict between Israel and Iran, the long shadow war, as people call it. This is an incident in that war.”

On the surface the second Israeli airstrike in Syria in two days and the third this year targeted Iranian missiles suspected of being transferred the Lebanese militant group Hezbollah.

"In last night's attack, as in the previous one, what was attacked were stores of Fateh-110 missiles that were in transit from Iran to Hezbollah," a Western intelligence source told Reuters.

The Associated Press notes that the Fateh-110 has a range of about 185 miles and is more accurate than anything Hezbollah is known to possess. With the missile, the Iranian proxy would have almost all of Israel in range and able precisely to target Israeli infrastructure and military installations.

"For Israel, it is very important that the front group for Iran, which is in Lebanon, needs to be stopped," Israeli lawmaker Shaul Mofaz told Israeli Army Radio. "Everything that goes into the hands of Hezbollah is not directly related to the rebels. ... [At the same time,] Hezbollah helps the Iranians navigate against the rebels."

Late Thursday Israel reportedly bombed a warehouse holding missiles at Damascus International Airport. In January Israel bombed the Jamraya military research facility near Damascus, which is the regime's main research center for work on biological and chemical weapons.

On the other hand, according to residents and activists, Sunday's strike hit about 10 targets including the mountain headquarters of the army’s Fourth Division, the elite and feared unit run by the president’s brother Maher, the command of the government’s elite Republican Guard, and the Jamraya military research facility.

"The sky was red all night. We didn't sleep a single second," one man told Reuters from Hameh, less than a mile from Jamraya. "The explosions started after midnight and continued through the night."

Syrian Deputy Foreign Minister Faisal al Mekdad said that the attack represented "declaration of war" and proved that Israel was acting "in support of terrorism and Al-Qaeda."

Syrian Information Minister Omran Zoabi said the act "opens the door to all possibilities."

An unnamed senior Israeli official told The Times that he doesn't expect Syria or Hezbollah to respond, saying that Assad “has his own problems” and Hezbollah "has no intention of opening a war in Israel.”

Nevertheless Spyer said that “one has to ask oneself about Israel’s calculus" because obviously “there is a risk in that at a certain point, a response becomes more likely.”

Some precautions have been taken by Israel as airspace over northern Israel and Haifa area closed off to civilian flights.

Lebanese media quoted Seyed Hassan Firouzabadi, the chief of staff of the Iranian armed forces, as saying: "Resistance forces will respond to the Israeli aggression… Iran will not allow to Israel destabilize the region."

Professor Eyal Zisser of Tel Aviv University summed it up to the Times like this: “Israel is still not involved in the war in Syria, but it is getting closer.”

Here's a video of the aftermath: