The fighting continues in Syria and neither side seems capable of gaining the upper hand in an increasingly bitter and perhaps unwinnable internecine war.

Yesterday rebel forces were again in action in the northern city of Aleppo, which has been much fought over recently.

According to reports which may not be reliable, the rebels had managed to seize the southern district of Sheikh Said which would give them access to the international airport, a key position, and were able to hold on to it after government forces withdrew after several days of fighting. At the same time government forces were reported to be in action south of Damascus, bombarding the rebel enclave of Moadamiyet al-Sham.

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In an attempt to break the deadlock, a security conference is being held in Munich this weekend to discuss the emergency and ways of ending it. During the opening session on Friday the UN and Arab League envoy for Syria, Lakhdar Brahimi, made it clear this was very much "the last appeal" and that delegates would have to work extra hard if a resolution were to be found.

Claiming that neither the people of Syria nor its regional neighbours were able to find a solution, he added "all that is left is the wider international world - please do your job."

Mouaz al-Khatib, Syria's opposition leader who is also attending the conference, said on the opening day that, while he was willing to sit down for talks with Assad's government, a pre-condition would be the release of all those who had been detained, thought to number at least 160,000.

As this condition is unlikely to be met and Russia will almost certainly be unwilling to change its policy, there is not much likelihood of any diplomatic solution in Munich.

Because nothing ever happens in isolation in this part of the world, the Israeli decision to involve itself in the Syrian civil war by attacking a military target has increased regional tensions especially in Iran which is Syria's principal regional ally.

The convoy in question was suspected of carrying sophisticated SA-17 anti-aircraft missile systems into Lebanon where the Israelis feared that they might fall into the hands of Hezbollah, the Shia militant group and political party which receives support from both Syria and Iran. If this happened Hezbollah would be in a position to use the missiles against Israeli warplanes and prevent them from flying so freely in Syrian air-space.

"Israel has set red lines regarding the transfer of certain kinds of weaponry to Hezbollah and if these lines are crossed it will enforce them as quietly and as inconspicuously as possible," claims Jonathan Spyer, a political analyst at the think-tank Centre Herzliya. "It doesn't want to humiliate the other side so they don't feel the necessity to respond."

Although the IDF refuses to confirm that an attack took place and there is still some confusion about the target and the way in which it was attacked the military deployments along the border suggest the Israelis are taking seriously the possibility that Syria or Hezbollah backed by Iran will retaliate by launching attacks from Syria's southern border into Israel.

Israel's armed forces are not known for giving their enemies any warning of an imminent attack. Surprise, power, speed and aggression are the usual hallmarks of their determination to engage any potential foe thought to be endangering the homeland. That is why last week's attack on a Syrian arms convoy is unlikely to be the last incident in an increasingly tense standoff between these two Middle Eastern neighbours and rivals.

"The world knows by now that Israel is no-one's patsy," says a US diplomatic source with long experience of working in the Middle East. "If their intelligence people had information that weapons were being moved into Lebanon, they weren't going to sit by and watch it all happening. That would explain the pre-emptive strike and also why they are being so edgy about it."

It is also clear that all contingencies are now being examined and acted upon by the Israelis. By the end of last week the Israeli Defence Force had increased the number of air combat patrols flying over the border with Syria and had moved up additional forces, including armour and artillery to the Golan Heights, the troubled mountain barrier between the two countries which has been under Israeli civil administration since 1981.

To protect those interests and maintain the territorial integrity of its homeland, Israel operates a "red-line" policy which insists that potential enemies should not be in a position to possess any kind of superior weaponry that can threaten Israel and its people.

The policy was put into context last week by Israel's Deputy Prime Minister Silvan Shalom when he made the following statement: "We have been monitoring for a long time the possibility that chemical weapons will fall into the hands of extremist rebels or, worse, into the hands of Hezbollah."

He added that if an enemy such as Hezbollah was to acquire chemical weapons, it would be "a crossing of all red lines that would require a different approach, including even preventative operations - the concept, in principle, is that this must not happen."

At the end of last week Syria's ambassador to Lebanon Ali Abdul Karim increased tensions when he claimed that his country reserves the right to make a "surprise retaliation" against Israel and that while he would not make further claims or statements, "this depends on the relevant authorities to decide on appropriate retaliation and decide the manner and place."

The Israeli Defence Force (IDF) seems to be taking the threat seriously as, in addition to the increased military presence on the ground, it has also moved up three batteries of Iron Dome air defence missiles which are capable of destroying incoming short-range missiles and shells.

The presence of this shield, which has already proved itself on the Gaza front by shooting down hundreds of rockets earlier in the year, has steadied nerves in northern Israel and provided confidence to the civilian population which will remember the last time Hezbollah attacked in 2008, firing thousands of short-range missiles over the border causing a huge amount of damage and almost triggering an outright war.

In a revealing display of self-confidence Major-General Eyal Ben Reuven, the deputy commander of Israel's northern command, appeared on national radio to claim that Israel's enemies to its north were little more than paper tigers and that the threat had been neutralised by the arrival of the Iron Dome missiles.

"I agreed to go on air first of all to tell those planning to go up north to enjoy the water and the snow, that they should go and enjoy it," he said, referring to the area's winter sports facilities. "The likelihood of a response in the short term is very low. The Syrians are weak - Hezbollah is in distress. The entire axis of evil is coming apart."

While the general's air of calm has reassured people in the north, the reality is that nothing has been resolved by the Israeli air strike and as long as the civil war in Syria rages there is a strong possibility the violence will suck in other players.

Yesterday saw the arrival in Damascus of Saeed Jalili, the chairman of the Iranian Supreme National Security Council for meetings with Syrian Prime Minister Wael al-Halqi and Foreign Minister Walid al-Muallem, and last week three-way talks were also held in Damascus between Syrian and Iranian officials and representatives of Hezbollah.

The flurry of diplomatic activity has reawakened fears within Israel that chemical or biological weapons could be used in an attempt to quell the insurrection against the regime of President Bashar al-Assad, which has lasted almost two years and claimed more than 60,000 lives.

Defence officials in Damascus have never ruled out that possibility and it remains a live threat. If that were to happen the consequences for Israel would be obvious as Iran has already threatened Israel with an attack by the nuclear weapons it is thought to be developing in its much criticised nuclear programme.

That will help to explain why Israel's prime minister Benjamin Netanyahu reminded his cabinet that, at a time of political uncertainty following last month's inconclusive election, they had to be guarded on all fronts: "We must look around us, at what is happening in Iran and its proxies and at what is happening in other areas, with the deadly weapons in Syria, which is increasingly coming apart."

Not surprisingly perhaps, given Russia's long-standing support for Assad's regime, the Israeli military intervention brought swift condemnation from Moscow where the Russian Foreign Ministry has warned that any escalation of the Syrian civil war could spark a regional conflict.

"If this information is confirmed, then we are dealing with unprovoked attacks on targets on the territory of a sovereign country, which blatantly violates the UN charter and is unacceptable, no matter the motives to justify it," said a Russian diplomat when Syria produced evidence its convoy had been bombed by Israeli planes.

Russia's intransigence over Syria remains the main stumbling block to prevent outside bodies brokering an end to the Syrian civil war.

Moscow has refused to countenance any move which smacks of outside interference in the country's affairs particularly if it is predicated on the ousting of President Assad.

There are two reasons why Moscow is taking such a hard line over what looks like a reasonable policy of ending a civil war which is causing major hardship to the civilian population. The first is that it is suspicious of US motives within the UN Security Council – its long-standing support for Israel and its past policies of regime change in Iraq and Afghanistan. The second is that Syria is a major customer for arms sales and an ally of Iran, another Russian sphere of influence in the Middle East.