Targeted assassination

It is exactly four years after the March 2004 train bombings in Madrid, and in the battle to contain a long-term threat from angry Muslim extremists, the United States and its allies are turning to the hugely controversial tactic pioneered by Israel -- 'targeted assassination.'

Few would argue the utilitarian strategy of tracking and killing terrorist leaders. Yet experience shows that the efficacy of 'taking out' a group's top commanders varies according to circumstances. Sometimes the whole movement crumples and disintegrates; on other occasions, the snake's head grows back. Everything depends on the group's hierarchy and links with a pool of supporters.

US and Israeli successes

Israel's decapitation strategy significantly cut the country's casualties from its peak of over 100 per month during the Second Intifada, which was declared in 2000. Opinion polls show that it earned a high degree of support among the Israeli public as a result.

With its hugely expensive war fighting apparatus, the United States can attempt to use the same tactic in the multiple fronts of its so-called War on Terror.

Attempted strikes against Osama Bin Laden have not hit home -- although a 1998 cruise missile strike is understood to have missed by a matter of minutes.

In January, a Predator unmanned aerial vehicle (UAV) succeeded in blowing up Abu Laith al Libi, a senior Taliban commander and the scourge of coalition troops in Afghanistan. Suspected terrorists in Yemen, Somalia and Iraq have also been the target of such strikes.

Results may vary

Targeted assassination tactics have also been used against the militant Kurdistan Workers' Party (PKK) and the Shining Path in Peru, with varying results.

• PKK guerrillas ravaged Turkey's cities and towns in the 1980s in pursuit of a homeland for the Kurdish people.  Tens of thousands died. Its leader, Abdullah Ocalan, was captured in 1999. A 'ceasefire' followed, and its operations ground to a halt. Yet the ceasefire began to wear thin in 2003, and the past year again saw violence, prompting Turkey's incursion into northern Iraq.
• An estimated 69,000 people died during a 20-year fight between the Shining Path, a Maoist insurgent group, and Peru's military. Peruvian intelligence eventually concluded that it had a key weakness: over-dependence on the charismatic leadership of its founder, the academic-turned warrior Abimael Guzman. After clever police work resulted in his arrest, the Shining Path never recovered.

The story is different when terrorist groups are enmeshed in a community that shares their grievance. Neither Hamas nor Hezbollah, for instance, have proved vulnerable to a knockout blow. Organised succession plans and a steady flow of sympathisers, swelled by revenge-thirsty relatives of dead civilians, mean that a heavy attrition rate is necessary to put a dent in leadership.

Missing the target

Some assassination attempts hit the wrong target, fanning greater desire for revenge against aggrieved communities. A US submarine recently lobbed two Tomahawk missiles into the village of Dhoble in Somalia. According to US military officials, the target of the attack was an al-Qaida leader. There have been reports of dead villagers, but it is as yet unclear if these casualties were targets or civilians.

Such assaults jeopardise campaigns to win 'hearts and minds', revealing the utilitarian debate over targeted assassination. Is collateral damage a price worth paying if you have the chance to cut off the snake's head?