Syria has introduced significant changes in the advanced model of the Scud D missile that gives it greater guidance capability and accuracy, according to Western missile experts.

The evaluations were based on an examination of pieces of a Scud D missile that went off course after a test launch and landed in southern Turkey.

The launch took place a few months ago, but it took some time until all the pieces were analyzed.

Meanwhile, Israel launched a successful Arrow missile Friday that intercepted a mock-up of an Iranian Shihab-3 missile. The goal of the test, the 14th launch of the Arrow, which is manufactured by the Rafael Armament Development Authority, was to expand its range to a higher altitude and to evaluate the interface between the Arrow and the Patriot missile system, which is to go into operation if the Arrow fails to shoot down its target.

Syria, in apologizing to the Turkish government after Ankara lodged a harsh protest over the Scud D launch, claimed that the mishap had resulted from human error. The missile landed in an open area, and no damage nor injuries were reported.

Two of the three Syrian missiles, which were launched from a site north of Haleb, were of the advanced D model, which has a range of 650 kilometers. The third missile was a Scud B, which has a 300-kilometer range.

Both the Turkish press and international media picked up the story of the errant Syrian Scud, engendering a great deal of interest in the U.S. and other countries following missile developments in the Middle East.

Turkey, a member of NATO, is closely following the development of land-to-land missiles both in Iran and Syria.

The warhead of the Scud D separates from its body on its way to the target. Course deviations in the warhead can be corrected with the addition of small wings of the same type found on SA-2 surface-to-air missiles, making the improved Scud much more accurate and allowing it to be aimed at smaller targets.

The upgrading of the Syrian Scud, advances in Iranian missiles and the test launch of the Israeli Arrow demonstrate that Syria and Iran are working on improving their missile capabilities. Israel, for its part, is focusing on its defensive capabilities.

The target of the Arrow test was launched from an Israel Airforce F-15 flying not far from Greece. The Arrow intercepted the target missile about 10 kilometers from the Israeli coast. "The success of the test improves existing operational capabilities of the Arrow system, which can successfully deal with future threats," Ya'akov Toren, director-general of the Defense Ministry, said.