HARSH TRAJECTORIES

Israel's ability to sustain prolonged around-the-clock air combat operations is partially due to fielding of sophisticated sensors. But the technology advance has not enabled the Israelis to avoid costly targeting missteps, or to suppress the Hezbollah rocket threat or pinpoint the adversary's weapons supplier.

Hezbollah rocket launchers have been a primary target for the Israeli air force's F-15s, F-16s and bevy of unmanned aircraft, which have all been fitted with electro-optical/infrared sensors to spot and engage those targets. And, while launchers are taken down daily, the rate of Hezbollah operations appears unaffected, and there are signs of potential escalation in the projectiles' lethality and range.

Moreover, information gathered by the airborne sensors is raising as many questions as it answers for military planners, particularly when it comes to identifying the main suppliers of weaponry to Hezbollah.

For instance, Israeli officials say most of the Hezbollah arms used appear linked to a Syrian supply chain, rather than an Iranian one--although the latter would also have to come through Syria. The strength of the Syrian connection is highlighted by the use of the 220mm. Urugan rockets, says an Israeli official. The weapon was developed by the Soviet Union, and has been exported to Syria.

Launchers seen in Lebanon differ from the Soviet design, with only one layer of four tubes rather than the standard three layers, two with six tubes and one with four. Officials suspect the change was made to accommodate a lighter vehicle.

But Israel isn't always certain where the weapons originated. For instance, while the 302mm. system resembles the Chinese WS-1 mounted on a more modern vehicle, the official says, it doesn't appear to be the Chinese system. Moreover, that configuration has not been seen in Iran, he adds, although the basic WS-1 has been exported there. The launchers feature two layers of three firing tubes each.

So far, four types of surface-to-surface unguided rockets have been identified, with the longest firing covering about 100 km. (62 mi.). This shot occurred from Lebanon's Bekaa Valley.

In addition to the launchers, the Israeli air force is targeting what it claims to be key elements of Hezbollah's infrastructure. The air force has been using U.S. GPS-guided bombs and possibly laser-guided GBU-28s, along with Israeli systems, likely including the Spice family of electro-optically guided 1,000- and 2000-lb.-class munitions.

One former Israeli air force officer points out most missions are being flown at night. "It's more than 50% and it's due to the technology. In the past, fighters have been restricted at night. In this war, night is not a factor," he says. In fact, night operations are better because the Hezbollah fighters feel protected by the darkness.