An Israeli report says Palestinian militants in the Hamas-ruled Gaza Strip have fired a shoulder-launched anti-aircraft missile against one of their warplanes, challenging for the first time Israel's long-held air supremacy, one of its most potent military strengths.

The Israeli military has not categorically confirmed the report Tuesday by the mass-circulation Yediot Aharonot, but Strategic Affairs Minister Yossi Kuperwasser, a former senior intelligence officer, says that "significant" numbers of advanced weapons have been smuggled into the Palestinian territory from Libya.

The Israelis have long suspected that Hamas and other militant factions in Gaza, which lies on Israel's southern flank on the Mediterranean coast, have acquired surface-to-air missiles looted from the late Moammar Gadhafi's armories during the 2011 Libyan war in which the longtime dictator was killed.

In 2011, the administration of U.S. President Barack Obama estimated that as many as 20,000 heat-seeking SAMs, most of them of Soviet or Russian origin, were unaccounted for in Libya.

NATO puts the figure closer to 10,000. Gen. Mohammed Adia, head of Libya's military chiefs, recently estimated 5,000 missiles were missing -- but that's still a lot of firepower.

Yediot Aharonot said that a Soviet-designed SA-7 Strela SAM was fired at an Israeli military helicopter last week, and missed.

In 2010, Israel's Elbit Systems, one of the Jewish state's leading military electronics manufacturers, unveiled a laser-based anti-missile system for civilian aircraft and helicopters, a version of which is fitted to military aircraft.

Civilian aircraft, including non-Israeli jets, are also at risk.

Al-Qaida fired two Strelas at an Israeli Arkia Airlines charter carrying 271 passengers and crew shortly after takeoff from Mombasa airport in Kenya Nov. 28, 2002.

Both SA-7s missed the Boeing 757.

Palestinian militants tried to shoot down an Israeli airliner over Rome in the 1970s, but so far no Israeli civilian aircraft has been hit, although hundreds of people have been killed in several other SAM attacks around the world over the last 40 years.

It's not clear if the attack on the helicopter over Gaza was thwarted by a defensive system, but the use of a SAM, even one as relatively unsophisticated as the Strela, marks a dangerous new threat to Israel's military aircraft from forces that for decades have had no effective counter-measures against air attacks.

The Israelis have been concerned that Hezbollah of Lebanon, Iran's main Arab proxy which fought Israel's military to a standstill in 34-day war in 2006, has also acquired SAMs from Iran via Syria, its regional ally which borders the movement's heartland in the Bekaa Valley of northeastern Lebanon.

The SAMs supposedly have been largely deployed around the launch sites and underground depots for the estimated 43,000 missiles and rockets the Israelis maintain Hezbollah possesses.

These would be primary targets for the Israeli air force if hostilities erupt again as Israeli leaders are determined to prevent a feared Hezbollah bombardment, which could last for several weeks with hundreds of missiles fired every day against Israeli cities.

In the first 36 hours of the 2006 war, the air force knocked out most of Hezbollah's longer-range weapons, but that did not stop an unprecedented bombardment of some 200 rockets a day hitting Israel's Galilee region, including the port city of Haifa.

Militants, mainly linked to al-Qaida, in Egypt's Sinai Peninsula, north of Gaza, are also reported to have acquired SAMs, although none has been spotted in action.

"The threat of anti-aircraft missiles is a serious worry, but it won't disrupt the air force's activities over Gaza," observed Yoram Schweitzer, a terrorism export with Israel's Institute for National Security Studies.

That may be so, but the presence of such weapons in any numbers with Hamas, Hezbollah and other militant groups along Israel's northern, southern and eastern borders could make anti-missile strikes like those carried out in 2006 much more costly for the Jewish state's forces.

The Oct. 6 shootdown of an Iranian-built Hezbollah unmanned aerial vehicle on an apparent surveillance mission over southern Israel, the first time an Arab drone has penetrated so deeply into the Jewish state, underlined the growing technological expertise of irregular forces long dismissed by Israel as low-tech adversaries.

The days when the Israelis can carry out air strikes against Hezbollah and the Palestinians with impunity could be drawing to an end.