HAIFA, Israel — The anti-aircraft missiles that were the target of a disputed Israeli airstrike on Syria this week were on a military base outside Damascus and had yet to reach the highway that leads to Lebanon when they were destroyed, two Israeli intelligence officials familiar with the air assault told McClatchy on Thursday.

The officials differed on the details, with one saying that the convoy carrying the missiles was parked at a military base in the Jamraya district outside Damascus, while the other said the convoy was in the process of being moved from the base to the highway. But both agreed that the location of the base, less than five miles from the Lebanese border, made Israeli officials unwilling to wait any longer to attack.

One said that waiting until the missiles had reached the highway, the main link between the Syrian capital and Lebanon’s capital, Beirut, would have made it more difficult for Israeli aircraft to target them without risking civilian casualties.

"What is important is that a convoy carrying weapons which would have been very dangerous for Israel was taken out before it could reach its target in Lebanon," said one of the officers, who’s based in Israel’s north. Both agreed to speak only on the condition of anonymity because they weren’t authorized to talk about the airstrike with journalists.

The Israeli officials’ accounts, if they’re accurate, help explain the Syrian government’s assertion that Israeli jets had targeted a scientific research center in Jamraya and not a military convoy when they flew low over the Israel-Syria border Wednesday in the pre-dawn hours. Syria said two workers were killed and five injured when the planes attacked.

The two versions of events also suggest that Israel not only is closely monitoring the location of Syria’s strategic weapons but also is willing to move to destroy them even before they’re on the verge of being transferred out of the control of Syria’s besieged government.

President Barack Obama has warned the regime of President Bashar Assad that it views the use of chemical weapons against anti-Assad rebels as a “red line” for possible military intervention. Israel’s threshold for taking action, as demonstrated Wednesday, appears to be much lower – and aimed at a much wider variety of potential threats.

Israeli officials have made it known for months that they fear that Syria’s sophisticated weapons systems might be passed willingly to the Islamist militants in Hezbollah, Israel’s arch-foe in Lebanon, or fall into the hands of al Qaida-linked militants who are now the vanguard of the anti-Assad rebellion.

Israeli officials told McClatchy that Wednesday’s attack was aimed at a convoy of Russian-made SA-17 anti-aircraft missiles that Israel feared were being sent to Lebanon. Russia apparently provided the weapons to Syria after Israeli aircraft destroyed a suspected nuclear reactor in Syria in 2007. One official told McClatchy that the missiles would have been a “game changer” had they fallen under the control of Hezbollah, which fought Israel to a standstill in 2006.

"Israel relies heavily on the strength of our air force, and its strategic deterrence," the official said. "Weapons systems that make our air force vulnerable will not be allowed to fall into the hands of terrorist groups."

On Thursday, other officials made it clear that Israeli concerns aren’t limited to anti-aircraft systems, citing specifically Russian-made SS-N-26 Yakhont anti-ship missiles, which Israeli officials said could target Israeli military and civilian shipping.

"The range and accuracy of these missiles is very threatening to Israel’s navy, and there is intelligence that Hezbollah has tried to obtain them in the past," said an military officer who also spoke to McClatchy on the condition of anonymity because of a lack of authorization to talk to journalists.

He said Russia had sold Syria 72 of the missiles, which can fly 180 miles at more than twice the speed of sound. From the coast of southern Lebanon, much of Israel’s naval fleet, including its port in the city of Haifa, would fall into range.

The Israeli officer stressed that to date, Yakhont missiles remained out of reach for Hezbollah.

"Hezbollah is always attempting to arm themselves, but we have made it clear that we consider certain weapons a red line and that we will act decisively to stop them from reaching Hezbollah’s hands," he said.

Israel has declined to publicly acknowledge Wednesday’s air raid, and American officials, who reportedly were told in advance of Israel’s plans to strike, have refused to comment.

Other usually well-informed sources on Syrian events have been unable to provide details of what took place. The Syrian Observatory for Human Rights, a London-based organization that tracks Syria’s civil war, said it could confirm that an airstrike had taken place but that it had been unable to determine the target.

Anti-government activists in Syria said they also had been unable to determine what had been struck. They noted that the area targeted is under government control and heavily fortified, and hadn’t been the subject of recent rebel activity.

Andrea Tenenti, a spokesman for the United Nations Interim Force in Lebanon, the U.N. group that’s charged with monitoring Hezbollah’s activities in southern Lebanon, told McClatchy that "nothing had changed in the area under UNIFIL’s mandate in recent weeks."

"We can certainly confirm that there were a high number of Israeli overflights that UNIFIL recorded yesterday. But that is all we have, and these air violations have continued on an almost daily basis. So we cannot draw any further conclusions on this basis," Tenenti said.

“We have not seen or witnessed smuggling of any weapons into southern Lebanon," he said.

Meanwhile, Israelis discounted Syrian threats that it would retaliate for the strike, saying the Assad government and its Hezbollah allies had neither the time nor the energy to engage with Israel as they battle the insurrection.

"It’s in the interest of Syria and Lebanon to let this thing die down slowly,” said Shlomo Brom, a senior researcher at the Institute for National Security Studies, an Israeli research center with close ties to the government. “Syria is coming apart, and the last thing they need is for Israel to come into the picture and further weaken and distract them. Hezbollah is also weaker than they have been in the past because of their commitments to Syria. They are concerned that if they get into a war they won’t be able to restock their weapons supplies through Syria as they did in the past."

McClatchy special correspondent David Enders contributed to this article from Beirut.

VIDEO: Pro-Assad Syrians Defiant Over Israeli Attack

Frenkel is a McClatchy special correspondent. Twitter: @sheeraf