That heightens fears that the Jewish state is edging closer to getting dragged into the Syrian bloodbath, which is now in its third year.
Israeli officials say the Jewish state's northern border is more tense than at any time since the cease-fire that ended the Yom Kippur War in October 1973.
Small arms fire, rockets and mortar shells launched from Syria, most probably by advancing rebel forces, continue to hit the western sector of the strategic volcanic plateau Israel first seized in the 1967 Middle East War.
It's not clear whether any of this fire was intentional or accidental but Israeli forces have retaliated at least five times since November and claim to have knocked out the sources of the fire.
The situation has worsened in recent days as the beleaguered regime of Syrian President Bashar Assad has pulled back large numbers of troops -- the Israelis estimate up to 20,000 -- from the Golan to beef up forces holding the capital against a widening rebel offensive.
Rebel forces have moved to expand a push against the city from the south. These are mainly jihadist fighters of the Jabhar al-Nusra, or the Nusra Front, who are allied to al-Qaida and have vowed to "liberate" Jerusalem from Israeli control.
"We see a deterioration of the general chain of command" in the Syrian-held sector of the Golan, said Lt. Col. Peter Lerner, an Israeli military spokesman.
But the Israelis see the main threat to them as the jihadists acquiring the regime's well-stocked arsenals of chemical weapons and advanced systems such as Russian-made Scud-B ballistic missiles, which can carry chemical warheads, and surface-to-air missiles that would challenge Israel's long-held air supremacy in the region.
Netanyahu, speaking in London where he attended the funeral of former British Prime Minister Margaret Thatcher Wednesday, stressed such weapons could be "game-changers" as far as Israel is concerned.
He stressed that Israel doesn't want to become involved in the Syrian bloodbath, in which by U.N. count 70,000 people have been killed since March 15, 2011, but won't hesitate to strike if it feels threatened.
The Israelis, and indeed Western and Arab powers as well, say that if the jihadists, the most effective rebel force, triumph they'll seek to further their ideological agenda by attacking Israel.
The regime's chemical and other weapons "are very, very dangerous weapons that could be game-changers," he said.
"They'll change the conditions, the balance of power in the Middle East. They could present a terrorist threat on a worldwide scale.
"It's definitely in our interest to defend ourselves but we also think it's in the interest of other countries," Netanyahu said.
"We're not aggressive. We don't seek military confrontation but we are prepared to defend ourselves if the need arises."
On Jan. 30, a convoy reportedly moving Russian-built SA-17 surface-to-air missiles from a Syrian depot into neighboring Lebanon for the Iranian-backed Hezbollah movement supporting Assad was destroyed in an airstrike.
Israel hasn't officially acknowledged or denied its air force was responsible but it's carried out similar attacks in Sudan on convoys carrying Iranian arms to Palestinian militants in Gaza.
Israel has warned it won't permit the Shiite fighters, who've been fighting the Jewish state for 30 years, to possess weapons that will for the first time allow them to challenge Israel's air superiority.
But if Israel gets involved in the Syrian conflict, it would greatly complicate the crisis and probably heighten the destabilization of the region that the war, increasingly sectarian in nature, is causing.
Israeli engagement, which Washington would no doubt seek to avoid, would probably have to be limited to airstrikes against a particular set of targets.
But airstrikes can't always do the job and Special Forces are often required. In 2011, the Israeli military formed a new command, the Deep Corps.
This is an amalgam of all its elite units and intelligence arms, including the army's Sayeret Matkal and the air force's Shaldaq unit.
However, covert ground operations would be a high-risk approach.