Israel's aerial assassination of the two top jihadist leaders in the Gaza Strip marked a major blow against al-Qaida in the Palestinian territory, which is seen as a growing threat because of ties to Islamist extremists in Egypt's increasingly lawless Sinai Peninsula.

On Saturday, Abu al-Walid al-Maqdisi, aka Hisham al-Saidani, a co-founder of the Mujahedin Shura Council, a jihadist umbrella group, and Ashraf al-Sabah, a leader of the Ansar al-Sunna group, were killed in an Israeli airstrike.

Israeli military sources said the two men, who had united all the jihadist groups in Gaza under the MSC around their own factions, were the de facto chieftains of the diffuse jihadist network in Hamas-ruled Gaza.

The Israelis have had limited conflict with al-Qaida since it was formed by Osama bin Laden in 1996, and that's been confined largely to Gaza.

But now they're seeing the jihadists as a growing threat on Israel's long- quiescent southern border, as the militants exploit the political upheavals ravaging the Arab world, making gains in Syria, to a lesser extent in Lebanon, and in the vast, desolate wastes of Sinai.

There, jihadists are joining forces with disgruntled Bedouin tribes long neglected by Cairo, and acquiring smuggled weapons looted from Muammar Gadhafi's armories during the Libyan war.

Jihadist groups have operated in Gaza for several years, but they've clashed with the mainstream, but militant, Hamas organization that has controlled Gaza since a coup against the mainstream forces of Palestinian President Mahmoud Abbas in June 2007, more than with Israel.

Salafist sources in Gaza say the jihadist groups, linked to al-Qaida, have vowed to avenge the assassination of Saidani and Sabah.

In response to Saidani's death, al-Qaida's media arm warned Israel its "joy will not last long."

Earlier, on Oct. 7, the Israelis killed two other prominent jihadists in Gaza, Talaat Halil Mohammed Jarbi and Abdullah Mohammed Hassan Maqawai.

Jarbi was also a member of the MSC, which the Israelis say is coordinating operations against them between jihadists in Gaza and other Islamic extremists in Sinai.

The Salafis consider Hamas, an offshoot of the Muslim Brotherhood and dedicated to the destruction of Israel, to be too moderate because it seeks to establish a Palestinian state.

The jihadists believe all Muslim states should be unified under an Islamic caliphate, hearkening back to the Muslim empire of the Middle Ages that stretched from Spain to Asia.

Since the February 2011 downfall of Egyptian dictator Hosni Mubarak, Sinai has become a hotbed of jihadist activity against both the new regime in Cairo and against Israel.

This has raised fears the new jihadist front against Israel could jeopardize the historic 1979 peace treaty with Egypt, which forbids Cairo from deploying military forces above a few battalions in the vast territory that lies between Israel and the Suez Canal.

Egypt's Muslim Brotherhood, which now holds the presidency and dominates parliament, has long opposed that treaty, along with most of Egypt's 82 million people.

But scrapping the pact, or demanding sweeping amendments that could disadvantage Israel, would jeopardize some $2 billion a year in U.S. aid.

Even so, the Israelis are becoming increasingly anxious about jihadists in Gaza coordinating attacks on the Jewish state through Sinai and perhaps triggering a clash with Egypt's new rulers that could spiral into something bigger.

A dozen Israelis have been killed in a string of recent well-planned and innovative attacks launched from Sinai, including Gaza-based militants.

For now, the Israelis are concentrating their counter-terrorism operations on the Gaza jihadists, largely because Israeli intelligence is deeply entrenched there and able to strike more or less with impunity, either to preempt jihadist operations or to retaliate for them.

Jarbi, identified by the Israelis as "global jihad operative," was said to be planning a "complex attack intended to take place along the Sinai border."

The Israelis said the same about Maqdisi, killed Saturday.

The Egyptians have responsibility for security in Sinai and they're not doing a very good job right now.

This irks the Israelis, but they can't afford to antagonize Cairo by mounting air strikes or commando raids in Sinai. So the jihadists in Gaza are in Israel's crosshairs.

Expect more assassinations -- unless Hamas, and Egypt, move hard against the jihadists.

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