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."