Palestinians have learned time and again over the six decades of their conflict with Israel that nothing is to be gained by using violence. No matter how determined their struggle, the Jewish state is far too powerful militarily and has an overwhelmingly influential political supporter in the US. It is therefore unsurprising that the militant faction Hamas' reckless decision to rain rockets and mortar shells on Israeli civilian targets, when a ceasefire ended a week ago, has been met with crushing brute force. The actions by both sides are to be denounced and concerted efforts should be made to end tensions. This is easier said than done. Negotiations are out of the question as long as Hamas refuses to recognise the right of Israel to exist. An Israeli blockade of its Gaza Strip heartland has caused understandable frustration. There cannot, however, be any excuse for Hamas firing on Israeli towns and villages. Israel has a right to defend its territory. It has been subjected to such attacks for years and has shown considerable restraint. That it has now lost patience with Hamas is understandable, but the waves of air strikes unleashed across Gaza over the past two days are out of proportion to the threat. Killing dozens of civilians in such a way, whether accidental or not, can never be condoned. Politics is helping drive Israel's response. Candidates in parliamentary elections on February 10 want to push a tough line to potential supporters. There are concerns that incoming US president Barack Obama will be more sympathetic to Palestinians than his predecessor, George W. Bush. Politicising a security and peace matter in such a way is dangerous. The UN Security Council's call yesterday for a halt to violence and military activities is welcome. Every effort must be made by the international community to separate the combatants and restore the truce. Israel must ensure that those hurt in its attacks can get medical help and allow humanitarian aid into Gaza. If there is to be peace, though, Israelis and Palestinians have only one choice: to settle differences through dialogue.