ISRAEL: Background, by Diplomatic Editor Trevor Royle

FROM a purely military point of view it's not difficult to understand why the Israeli Defence Forces (IDF) decided yesterday that retaliation was the best form of defence. All week long Hamas militants have been lobbing missiles and mortar rounds across the border and even the mildest-mannered neighbour might start to bridle at such behaviour. "Enough is enough" was the message in Jerusalem; the entire political spectrum from prime minister Ehud Olmert to foreign minister Tzipi Livni was singing from the same song sheet. With an election looming in February, prime ministerial hopefuls were keen to reinforce their tough-guy credentials.

Although there will be further Israeli counter-attacks this is unlikely to be a full-scale invasion. The IDF is not in the business of controlling enemy territory or policing a hostile people who elected Hamas in the first place. Instead, IDF units will continue to pinpoint known military sites and attempt to destroy the assets which were deployed to attack Israeli territory. The use of these tactics suggests that Israeli commanders have improved their intelligence-gathering operations and might even have infiltrated Hamas. If so, that would be a distinct coup as good real-time intelligence is a boon to any counter-insurgency operation of this kind.

However, this kind of military solution can only be a short-term fix. Force has been used in the past by both sides but to no avail. Hamas attacks result in Israeli counter-attacks, people on both sides are killed, positions become further entrenched and any solution disappears over the far horizon. The Israelis are usually seen to be the aggressors, so international opinion is outraged, and reason goes to the devil.

That's why the current round of Israeli attacks will not only achieve little but also have the potential to make matters much worse. Hamas is no longer the simple Iranian-bankrolled gang of terrorists it is painted as by Israeli commanders.

It has moved on from being a terrorist group whose ambitions extended only to rocket attacks and suicide bomb raids. It now has a militia of 15,000 troops, it has been being taking lessons from Hezbollah and, crucially, it has the backing of the people. That makes Hamas a formidable opponent and the last thing needed by the IDF is another slogging match along one of its frontiers, with Palestinian rocket teams being presented to the Arab world as righteous martyrs.

It's now getting to the stage, too, where international brokerage might be the only way to give the Palestinians what they want in Gaza, namely a settled existence with agreed working borders and access to the outside world. At the same time the Israelis must revisit the plans drawn up by Ariel Sharon in 2005 and impose his land-for-peace deal, this time by providing a security apparatus which prevents violence.

Even though the recent Egypt-brokered truce was honoured only in the breach - Hamas continued firing rockets and the Israelis were fitful in permitting the flow of goods into Gaza - an immediate ceasefire might provide the only practical diplomatic leverage to prevent further bloodshed. The time has come for the rest of the world to become serious about solving a problem which, to its disgrace, is now about to enter its seventh bloody decade.