By Christopher Hack Lebanon analyst

Fears are growing of a new military front opening in the Middle East, across Israel's northern border with Lebanon.

Such a development would turn the conflict into a more dangerous regional war, probably drawing in both Lebanon and Syria, and perhaps other nations.

In recent days, guerrillas of the Iranian-backed Lebanese Hezbollah movement have increased their sporadic attacks on Israeli positions across a disputed area of the border.

Israel has responded by shelling unoccupied areas on the Lebanese side of the border. But the Israeli Government has said if the attacks continue, it will broaden its retaliation.

Click here for map of border

In the past year, Hezbollah is believed to have built up a large arsenal of missiles in southern Lebanon, which if launched could paralyse northern Israel, reaching as far south as Haifa.

Any tit-for-tat exchange in which these missiles were launched would trigger a massive Israeli military operation against Lebanon - "turning it into a parking lot," according to one analyst.

Syrian power

Most Lebanese, including their own government, desperately want to avoid their country being sucked into the conflict.

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However, Lebanon is effectively controlled by its larger neighbour Syria, which along with Iran sponsors Hezbollah.

Damascus is frustrated with Israel's actions in the West Bank and Gaza, and also yearns for Israel to withdraw from the Golan Heights - a vast Syrian mountain plateau occupied since 1967.

Syria has long allowed Hezbollah to launch small cross-border attacks to maintain "military pressure".

However, analysts believe the ferocity of the Israeli offensive against the Palestinians in recent weeks has prompted Syria to let Hezbollah off the leash.

The devoutly Islamic guerrilla group came to prominence during its long campaign against Israel's occupation of south Lebanon.

These guerrilla attacks arguably prompted Israel to withdraw in May 2000, and have proven a model for Palestinian fighters.

After claiming victory in south Lebanon, Hezbollah took up the Palestinian cause six months later when the intifada began in October 2000, in part to maintain its sense of mission.

Brinkmanship

The Hezbollah leader, Sheikh Hassan Nasrallah, has in recent months increased this support, admitting trying to smuggle weapons to the Palestinians via Jordan.

Syria has about 30,000 troops in Lebanon

At the Arab League summit last month, he urged regional states to do likewise, saying the only option for the Palestinians was military "resistance".

In the current border stand-off, Hezbollah believes it is playing a clever strategic game, judging that Israel will not respond to its attacks because of fears of the group's rocket arsenal, and because it would not want to open a second front during hostilities with the Palestinians.

However, the Israeli leadership believes it is fighting a war for the country's survival, and will eventually respond to Hezbollah's attacks, whatever the cost.

Israeli military analysts have long said that a war with Hezbollah is inevitable to remove the missile threat from northern Israel.

It would also seem clear that after 11 September, and given the current supportive attitude of the Bush administration, Israel will never be in a better position to attack its enemies.

Pressure on Syria

There are still hopes of calming the situation and preventing a second front opening.

Syria is under international pressure to rein in Hezbollah.

Since January, Syria has held a two-year seat on the 15-member UN Security Council, and this is being used as a channel to apply diplomatic pressure.

Moderate Arab states such as Egypt, Saudi Arabia and Jordan will also use their influence to try and curb Hezbollah's attacks.

Given its battles with the Palestinians, Israel may also be prepared to continue overlooking the occasional border attack, so long as it does not suffer civilian casualties.

While the Israeli army is so heavily engaged in the West Bank and Gaza, opening a second front in the north would be very risky.

Equally, any brokered ceasefire between Israel and the Palestinians would serve to reduce tension on the border.

However, should Hezbollah continue its cross-border attacks, many analysts believe there is a growing risk that the current conflict between Israel and the Palestinians will escalate into a regional conflict, with the Lebanon-Israel border as the next flashpoint.