Israel struck an area near Damascus early Sunday morning, Syrian state television reported, the second such airstrike in 48 hours.

The Syrian report claimed Israeli rockets hit a military research site on the outskirts of the capital at about 2 a.m., and smoke could be seen rising from the area. An unnamed Israeli official told AFP the target was a shipment of Iranian made Fateh-110 missiles that were on their way from Syria to Hezbollah terrorists.

Uzi Rubin, a missile expert and former Defense Ministry official, told the Associated Press that if the target was a consignment of Fateh-110 missiles, then such weaponry did constitute a “game-changer”: Fired from Syria or south Lebanon, these missiles, he said, could reach almost anywhere in Israel with high accuracy.

Rubin emphasized that he was speaking as a rocket expert and had no details about the reported strikes.

“If fired from southern Lebanon, they can reach Tel Aviv and even [the southern city of] Beersheba,” Rubin said. He said the rockets are much five times more accurate than the Scud missiles that Hezbollah has fired in the past. “It is a game-changer because they are a threat to Israel’s infrastructure and military installations,” he said.

Syrian state-run news agency SANA said explosions went off at the Jamraya research center near Damascus, causing casualties and blackouts. “Initial reports point to these explosions being a result of Israeli missiles that targeted the research center in Jamraya,” SANA said.

The Jamraya site was the same one reportedly hit by Israeli planes in January.

An unnamed American official confirmed to NBC News that Israeli planes hit the facility, though a Pentagon spokeswoman said she had no information relating to the report. It wasn’t clear whether Israel alerted the US before the attack.

A Syrian activist group, the Britain-based Syrian Observatory for Human Rights, also reported large explosions in the area of Jamraya. It was not clear if this report, and various other reports of several more explosions in the area, were part of the same Israeli strike, or part of the ongoing civil war in Syria between regime and rebel forces.

Other activists, for instance, reported that a blast that hit an ammunition depot in the Qassiyoun mountains near the city. According to a Syrian official who spoke to Al Arabiya, the Syrian regime uses its bases on the mountain to fire missiles at rebel targets in Damascus.

“The mountain is a very strategic site that oversees all of Damascus,” said the source. “There is a heavy presence of the Assad forces in the mountain because they are always on-call to launch any possible attack towards the people of the city.”

Reuters quoted activists who said they saw jets in the sky over Damascus and that a missile brigade and troop battalions loyal to Assad had been hit.

Loud explosions shook the city and video put online claiming to be from the incident shows a series of large fireballs rising into the sky.

“Everything was quiet and suddenly we saw this bright orange light in the sky followed by a very loud explosion,” Tarek Hillnawi told the Al-Arabiya satellite television station. “I felt that it was over for us, that all of Damascus is set on fire.”

A spokesperson for the Free Syrian Army, speaking from Istanbul, told Al-Arabiya that six sites around Damascus had been hit.

Hezbollah’s al-Manar TV claimed an Israeli plane had been shot down over Damascus. There was no confirmation or evidence for the claim.

The Israel Defense Forces declined to comment on the reports and no special activity was recorded on Israel’s northern borders.

Prime Minister Benjamin Netanyahu was set to deapart for a historic visit to China Sunday.

Former IDF chief of staff, Kadima MK Shaul Mofaz, declined to comment on Sunday’s attack, but said he supported Israel’s policy of preventing weapons from reaching Hezbollah.

“One thing is clear, Syria is falling apart before our eyes. Iran and Hezbollah are deeply involved in the Syrian civil war and the transfer of weapons may be the regime’s way of thanking Hezbollah for siding with it in its fight against rebel groups,” Mofaz told Israel Radio.

On Saturday, unnamed Israeli officials confirmed Israel Air Force planes had carried out a strike against Syrian targets early Friday. The New York Times reported that advanced missiles from Iran en route to Shiite terror group Hezbollah were destroyed in that attack.

In late January, the IAF reportedly struck targets near the Scientific Studies and Research Center in Jamraya, outside Damascus. Last week the Wall Street Journal revealed that the attacking aircraft in that incident did not enter Syrian airspace. The same maneuver was reportedly used in the early Friday incident.

Iranian Fatah-110 missiles on display during a 2012 military exhibition in Tehran (photo credit: CC BY-SA, military.ir, Wikimedia Commons)

Iranian Fateh-110 missiles on display during a 2012 military exhibition in Tehran (photo credit: CC BY-SA, military.ir, Wikimedia Commons)

The missiles targeted on Friday were believed to be m600s, a Syrian version of Iran’s Fateh-110 missile, an extremely accurate guided missile capable of traveling roughly 300 kilometers (190 miles) with a half-ton warhead, an Israeli official said.

President Barack Obama said Saturday that he wouldn’t comment on the Israeli airstrike against Syria. He said it was up to Israel to confirm or deny any strikes, but that the US coordinates very closely with Israel.

“The Israelis, justifiably, have to guard against the transfer of advanced weaponry to terrorist organizations like Hezbollah,” Obama told the Spanish-language TV station Telemundo.

Fighting has repeatedly spilled across Syria’s borders into Turkey, Lebanon, Iraq, Jordan and the Israeli-annexed Golan Heights during more than two years of conflict, while more than 1 million Syrians have sought refuge in neighboring countries.

The airstrikes came as Washington considers how to respond to indications that the Syrian regime may have used chemical weapons in its civil war. Obama has described the use of such weapons as a “red line,” and the administration is weighing its options — including possible military action.

Israel has said it wants to stay out of the brutal Syria war, but could inadvertently be drawn in as it tries to bolster its deterrence and prevent sophisticated weapons from flowing from Syria to Hezbollah or other extremist groups.

Amos Gilad, an Israeli defense official, would not confirm or deny Friday’s airstrike, but played down cross-border tensions.

Hezbollah has not obtained any of Syria’s large chemical weapons arsenal and is not interested in such weapons, Gilad said. Instead, the militia is “enthusiastic about other weapons systems and rockets that reach here (Israel),” he said Saturday in a speech in southern Israel.

Assad “is not provoking Israel and the incidents along the border (between Syria and the Israeli-controlled Golan) are coincidental,” Gilad said.

After Hezbollah’s military infrastructure was badly hit during the 2006 war, the group was rearmed by Iran and Syria — with Tehran sending the weapons and Damascus providing the overland supply route to Lebanon.

“This is a very sophisticated network of Iranian arms, Syrian collection, storage, distribution and transportation to Hezbollah,” said Salman Shaikh, director of The Brookings Doha Center and in 2007 involved in U.N. weapons monitoring in Lebanon.

Shaikh said Israel had detailed knowledge of weapons shipments to Hezbollah at the time and most likely has good intelligence now. “The Israelis are watching like hawks to see what happens to these weapons,” he said.

With Israel apparently enforcing its red lines, much now depends on the response from Hezbollah and Syria, analysts said.

Israeli officials have long feared that Assad may try to draw Israel into the civil war in hopes of diverting attention and perhaps rallying Arab support behind him.

But retaliation for Israeli airstrikes would come at a high price, said Moshe Maoz, an Israeli expert on Syria.

“Bashar has his own problems and he knows that conflict with Israel would cause the collapse of his regime,” Maoz said. “He could have done that long ago, but he knows he will fall if Israel gets involved.”

Hezbollah, which is fighting alongside Assad’s troops, appears to have linked its fate to the survival of the Syrian regime. Nasrallah, the Hezbollah chief, said this week that Syria’s allies “will not allow Syria to fall into the hands of America or Israel.”

On the other hand, Hezbollah could endanger its position as Lebanon’s main political and military force if it confronts Israel, and it’s not clear if the militia is willing to take that risk.

Hezbollah isn’t Israel’s only concern. Israeli officials believe it is only a matter of time before Assad’s government collapse, and they fear that some of the Islamic extremist groups battling him will turn their attention toward Israel once Assad is gone.

Reflecting Israel’s anxiety, the Israeli military called up several thousand reservists earlier this week for what it called a “surprise” military exercise on its border with Lebanon.

Obama has said the use of chemical weapons would have “enormous consequences,” but has also said he needed more definitive proof before making a decision about how to respond.