Israel's air force commander, whose warplanes hit targets in Syria three times this year, warned that his squadrons could soon be in a "surprise war" with Syria as Russia bolsters the embattled Damascus regime with new missiles.

Israeli Maj. Gen. Amir Eshel said the "immense arsenal" that Syrian President Bashar Assad has built up in recent months with Russian and Iranian weapons means that Israeli forces could find themselves in combat at any moment against a more aggressive Syrian regime.

"These days a number of scenarios can lead to a surprise war," he told a security conference outside Tel Aviv Wednesday.

His warning came after Israeli Prime Minister Binyamin Netanyahu was bluntly rebuffed by Russian President Vladimir Putin when the Israeli leader flew to see Putin at his holiday villa on the Black Sea to ask that he not supply Assad with powerful S-300 anti-aircraft missiles.

The Americans too have sought to persuade Moscow not to deliver the S-300s and met with a similar Russian response.

That was hardly surprising since only a month ago the Pentagon announced plans to sell Israel, Saudi Arabia and the United Arab Emirates air-defense missiles and other weapons worth $100 billion.

Eshel says the S-300PMUs will "soon" arrive in Syria. He gave no numbers but Moscow has said the deal is worth some $900 million, which would probably involve six or seven batteries and perhaps 150 missiles.

It could be several weeks before they're operational but they will greatly enhance Assad's air defenses and pose a serious challenge to Israel's long-held air supremacy in the region.

The S-300 is one of the most potent air-defense systems. It can track up to 100 targets, aircraft and missiles, simultaneously, engage 12 of them at a time and hit targets at altitudes of 20 miles at a range of 95 miles.

These weapons could also make it difficult to enforce a Western-backed, no-fly zone around Syria to prevent the regime using its air power against rebel forces.

The Syrians have built up air defenses into a formidable force with Russian systems since Sept. 6, 2007, when seven Israeli F-15Is destroyed a nuclear reactor in eastern Syria that the North Koreans were building.

A year ago, the Israelis and Americans talked Moscow into holding up delivery of five S-300 batteries to Iran, a vital Syrian ally, which wanted the missiles to protect its nuclear facilities against preventive airstrikes Israel had threatened to launch.

But this time, Putin cannot afford to step back to accommodate the Western powers as he seeks to rebuild Moscow's influence in the Middle East and the Mediterranean.

He has leveraged Russia into a key position in the intense diplomacy over Syria's future and isn't prepared to relinquish that.

Moscow reportedly has already delivered an unknown number of P-800 Yakhont anti-ship missiles, which could bolster heavy defenses around the Syrian naval bases at Latakia and Tartus.

The Russian navy has a base at Tartus, used by a dozen Russian warships sent to patrol the eastern Mediterranean to display Moscow's support for Assad and to warn the West and Israel not to intervene in Syria's civil war.

The hard-to-detect P-800, the export version of the Oniks missile, has a range of up to 187 miles and carries a 550-pound warhead.

So far, Israel's three airstrikes, which began Jan. 30, have been aimed at missile shipments destined for Hezbollah in Lebanon for use against Israel at some future date.

Israel has sought to avoid direct involvement in the civil war itself but its military chiefs have been hinting strongly that if Damascus seeks to make trouble in the Israeli-occupied Golan Heights in southern Syria, that could change.

It's probably no coincidence Eshel's warning came after Damascus acknowledged its forces fired on an Israeli jeep in the Golan Tuesday. That was the first time the regime has admitted firing on Israelis in the current conflict.

Israel retaliated by destroying the Syrian position with a missile.

Israeli analyst Ehud Yaari, a leading Arab affairs expert, warned the northern border was "several times more explosive than it was."

He said this marked a serious change of policy by Assad, who's now tied to "committing himself to respond to any future Israeli attacks."